I'm afraid simple optimization like RAM cleaning will not work in your case. Looks like your device has enough RAM to play, otherwise the game would just quit itself. The only reason of low FPS I see, not enough power of your chipset (CPU+GPU).
This game does require a high performance phone, mainly because of the fluid simulations in the private scenes. I know it only partially runs on the Samsung Galaxy S10 (with Snapdragon 855), which means even more powerful models are required. I specified the Snapdragon 865 or Samsung Exynos 1080 as a minimum, but the newer is better.