S10 Game Resolution

Guys, can you tell me PLEASE how can I change resolution of games cuz they seem to use low resolution even if i set the screen to WQHD+ I can see pixels and it looks like 720p not 1440p. On my old S8+ i was so annoyed that i has 2k resolution screen but games are running in HD, so i did search a lot and i found Game Tuner app which allows you to change games resolution and also performance. This app changed everything! Games did not have lags and picture was very sharp with 1440p resolution. Now I'm using S10+ and Game Tuner is not available and i can't find anything to work like on my S8+. PLEASE HELP ME!!! One thing I don't understand, S10+ is the most powerful android phone and has 1440p screen but i can't play games with this resolution because they will lag???