LOL, first off, triple 4K displays are 3 times the pixels driven by the GPU, so you need WAY more than a "4K GPU" to run it. It also goes without saying that the words cheap and triple 4K do not mix well.
Even a $1500 RTX 3090 struggles a bit with triple 4K on modern games when using max settings. We're talking at best 55 FPS at just High vs max settings on Far Cry 5. Triple 1440p is far more practical, but some games, like CoD Modern Warfare, don't support that res.
The following video demonstrates it pretty well. Jump to the 12:45 mark for the triple screen game testing. Do watch the whole video though, because he goes through his spec, and his CPU is also quite powerful.
That said, Wolfenstein Youngblood ran very well in full triple 4K res, and at well over 100 FPS. That may very well be due to the fact that the game is running on the Vulkan API, so other games that run on Vulkan, like Doom Eternal, Mad Max, etc, may also perform quite well.