What hevc nvenc settings do work with lossless preset in ffmpeg?

[qo4on]

It seems that adding this command improves compression a bit:

-profile rext -rc-lookahead 32 -refs:v 16 -bf 3

What else can be tuned with lossless preset?

[ProWo]

for all options create a new textfile named hevc_info.cmd with the following 2 lines:
ffmpeg.exe -h encoder=hevc_nvenc
pause

execute it

[qo4on]

for all options create a new textfile named hevc_info.cmd with the following 2 lines:
ffmpeg.exe -h encoder=hevc_nvenc
pause

execute it

Which options?
ffmpeg.exe -h encoder=hevc_nvenc doesn't show info about lossless:

Encoder hevc_nvenc [NVIDIA NVENC hevc encoder]:
    General capabilities: delay hardware
    Threading capabilities: none
    Supported pixel formats: yuv420p nv12 p010le yuv444p p016le yuv444p16le bgr0 rgb0 cuda d3d11
hevc_nvenc AVOptions:
  -preset            <int>        E..V...... Set the encoding preset (from 0 to 11) (default medium)
     default         0            E..V......
     slow            1            E..V...... hq 2 passes
     medium          2            E..V...... hq 1 pass
     fast            3            E..V...... hp 1 pass
     hp              4            E..V......
     hq              5            E..V......
     bd              6            E..V......
     ll              7            E..V...... low latency
     llhq            8            E..V...... low latency hq
     llhp            9            E..V...... low latency hp
     lossless        10           E..V...... lossless
     losslesshp      11           E..V...... lossless hp
  -profile           <int>        E..V...... Set the encoding profile (from 0 to 4) (default main)
     main            0            E..V......
     main10          1            E..V......
     rext            2            E..V......
  -level             <int>        E..V...... Set the encoding level restriction (from 0 to 186) (default auto)
     auto            0            E..V......
     1               30           E..V......
     1.0             30           E..V......
     2               60           E..V......
     2.0             60           E..V......
     2.1             63           E..V......
     3               90           E..V......
     3.0             90           E..V......
     3.1             93           E..V......
     4               120          E..V......
     4.0             120          E..V......
     4.1             123          E..V......
     5               150          E..V......
     5.0             150          E..V......
     5.1             153          E..V......
     5.2             156          E..V......
     6               180          E..V......
     6.0             180          E..V......
     6.1             183          E..V......
     6.2             186          E..V......
  -tier              <int>        E..V...... Set the encoding tier (from 0 to 1) (default main)
     main            0            E..V......
     high            1            E..V......
  -rc                <int>        E..V...... Override the preset rate-control (from -1 to INT_MAX) (default -1)
     constqp         0            E..V...... Constant QP mode
     vbr             1            E..V...... Variable bitrate mode
     cbr             2            E..V...... Constant bitrate mode
     vbr_minqp       8388612      E..V...... Variable bitrate mode with MinQP (deprecated)
     ll_2pass_quality 8388616      E..V...... Multi-pass optimized for image quality (deprecated)
     ll_2pass_size   8388624      E..V...... Multi-pass optimized for constant frame size (deprecated)
     vbr_2pass       8388640      E..V...... Multi-pass variable bitrate mode (deprecated)
     cbr_ld_hq       8            E..V...... Constant bitrate low delay high quality mode
     cbr_hq          16           E..V...... Constant bitrate high quality mode
     vbr_hq          32           E..V...... Variable bitrate high quality mode
  -rc-lookahead      <int>        E..V...... Number of frames to look ahead for rate-control (from 0 to INT_MAX) (default 0)
  -surfaces          <int>        E..V...... Number of concurrent surfaces (from 0 to 64) (default 0)
  -cbr               <boolean>    E..V...... Use cbr encoding mode (default false)
  -2pass             <boolean>    E..V...... Use 2pass encoding mode (default auto)
  -gpu               <int>        E..V...... Selects which NVENC capable GPU to use. First GPU is 0, second is 1, and so on. (from -2 to INT_MAX) (default any)
     any             -1           E..V...... Pick the first device available
     list            -2           E..V...... List the available devices
  -delay             <int>        E..V...... Delay frame output by the given amount of frames (from 0 to INT_MAX) (default INT_MAX)
  -no-scenecut       <boolean>    E..V...... When lookahead is enabled, set this to 1 to disable adaptive I-frame insertion at scene cuts (default false)
  -forced-idr        <boolean>    E..V...... If forcing keyframes, force them as IDR frames. (default false)
  -spatial_aq        <boolean>    E..V...... set to 1 to enable Spatial AQ (default false)
  -temporal_aq       <boolean>    E..V...... set to 1 to enable Temporal AQ (default false)
  -zerolatency       <boolean>    E..V...... Set 1 to indicate zero latency operation (no reordering delay) (default false)
  -nonref_p          <boolean>    E..V...... Set this to 1 to enable automatic insertion of non-reference P-frames (default false)
  -strict_gop        <boolean>    E..V...... Set 1 to minimize GOP-to-GOP rate fluctuations (default false)
  -aq-strength       <int>        E..V...... When Spatial AQ is enabled, this field is used to specify AQ strength. AQ strength scale is from 1 (low) - 15 (aggressive) (from 1 to 15) (default 8)
  -cq                <float>      E..V...... Set target quality level (0 to 51, 0 means automatic) for constant quality mode in VBR rate control (from 0 to 51) (default 0)
  -aud               <boolean>    E..V...... Use access unit delimiters (default false)
  -bluray-compat     <boolean>    E..V...... Bluray compatibility workarounds (default false)
  -init_qpP          <int>        E..V...... Initial QP value for P frame (from -1 to 51) (default -1)
  -init_qpB          <int>        E..V...... Initial QP value for B frame (from -1 to 51) (default -1)
  -init_qpI          <int>        E..V...... Initial QP value for I frame (from -1 to 51) (default -1)
  -qp                <int>        E..V...... Constant quantization parameter rate control method (from -1 to 51) (default -1)
  -weighted_pred     <int>        E..V...... Set 1 to enable weighted prediction (from 0 to 1) (default 0)
  -b_ref_mode        <int>        E..V...... Use B frames as references (from 0 to 2) (default disabled)
     disabled        0            E..V...... B frames will not be used for reference
     each            1            E..V...... Each B frame will be used for reference
     middle          2            E..V...... Only (number of B frames)/2 will be used for reference
  -dpb_size          <int>        E..V...... Specifies the DPB size used for encoding (0 means automatic) (from 0 to INT_MAX) (default 0)

[ProWo]

Read your output:
lossless 10 E..V...... lossless
losslesshp 11 E..V...... lossless hp