How to adjust brightness on LG B4 OLED?

This may be a dumb question, but I recently (around November) got an lg b4 oled tv, and I do really like it aside from some aggressive auto dimming that I don’t think is actually too big of a problem.

The only actual problem I have is I cannot find the actual brightness slider. Oled pixel brightness is all I can find, but I saw posts of people saying set pixel brightness to number and tv brightness to number, and this whole time I thought pixel brightness WAS the tv brightness. So where is the actual brightness slider?

I found a setting called “gamma (adjust brightness)”, but it’s grayed out and I don’t know how to access it. I really only use this tv for playing games, which I saw hdr game settings seems to lock a bunch of the picture settings, but why would they lock tv brightness? Am I missing something? Thanks for any help