The x264 encoder supports both 4:4:4 as well as 4:2:0, as long as the underlying hardware is fast enough to handle it. It also has two different ways to reach each quality level: Constant Quantization Parameter (CQP) and Constant Rate Factor (CRF). Unfortunately OBS Studio only offers the latter, so for now we are stuck with that.
With a single-PC setup, 4:4:4 recording using CRF will be very difficult. You might have to lower the preset used in order to maintain reasonable performance in game and encodes. Note that OBS Studio must be assigned a higher priority than the game.
x264 does not support True Lossless due to how the H.264 codec works.