It’s an adapter 😉

Depends on the source, What GPU will you use.

But in general, HDR is supported Gsync is not.

Remember to use a certified HDMI cable with the adapter like the CAC-1372

https://www.club-3d.com/en/detail/2460/ultra_high_speed_hdmi_4k120hz_8k60hz_certified_cable_48gbps_m-m_2_m_-_6.56_ft/

1080ti 

1080 Ti is Pascal generation. It doesn’t support DSC so you’ll be limited to DisplayPort 1.4 non-DSC modes (4:4:4 or chroma sub sampling modes 4:2:2 or 4:2:0).

Without DSC, 4K120 is not possible with DisplayPort 1.4 unless you reduce the pixel clock from HDMI’s 1188MHz down to under 1080MHz for 4:4:4 8bpc (such as CVT-RB2’s 1076 MHz) or you use 4:2:2 10bpc (which may be necessary if HDR requires 10bpc).

4K120 4:2:0 8bpc can work with HDMI 2.0 signalling.

I think the TV has a method to show the input signal type.

https://forums.macrumors.com/threads/mac-mini-4k-120hz.2267035/post-30639700

https://www.youtube.com/watch?v=H4CCcvtnjj8

https://www.reddit.com/r/OLED/comments/jaqc6y/with_the_new_lg_oled_tvs_how_do_you_display/

TM = TMDS = HDMI 2.0

4L10 = 4 lanes of 10Gbps each = HDMI 2.1 (but not the highest speed 4L12)