I use RTings.com for TV settings. Doesn't have every TV but has the best ones.I just use this guys recommendation for picture settings and they suit me but maybe not suit others.
Also I think dull HDR images are mainly down to cheap TVs having poor peak brightness(nits).
LG TV picture settings.
LG 2017-2024 OLEDs - Optimized Settings for Xbox One/Series X|S, PS4/PS5, Switch, PC and webOS/Movies (SDR, HDR, DV) Sony - Microsoft - Tech
AVS forums owners threads are good as well :
LCD and LEDs : LCD Flat Panel Displays
OLEDs : OLED Technology and Flat Panels General