Make game use more GPU cores?

I’ve noticed severe FPS drops during some scenes and found out that game engine uses only 1 of all provided by GPU cores.
For example RX 6900XT has 16 cores. Game uses only 1 (!). Other 3 blocks are used maybe by OS, while other 12 are idling.
Is there a way to make it use 100% of GPU power? Any game engine \ game config \ OS \ driver update?