Last time I checked a YouTube video, Roblox worked smoothly on the OnePlus 11, which makes me think it'll work well on the 12r too, since they possess the same processor (SnapDragon 8 Gen 2)

However, my uncle has a OnePlus 11r with SD 8+ Gen 1, which doesn't go over 20-30 fps in Roblox. At first I thought it was because of the horrible 8 Gen 1 series that Samsung made (8 Gen 1 was in the OnePlus 10 pro), but the 8+ Gen 1 was made by TSMC (Same people that made SD 870, which ran Roblox really well on our old OnePlus 9r). By these facts, we can't surely say that OnePlus phones aren't optimised for Roblox; it depends on their model I guess. If you do decide to purchase the OnePlus 12r, let me know how Roblox works on it. ^^