Not sure what you mean by "fine", but M4 mini can handle multiple 4k monitors at once with 60Hz. Check its specifications Apple provides:
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Simultaneously supports up to three displays:
- Up to three displays: Two displays with up to 6K resolution at 60Hz over Thunderbolt and one display with up to 5K resolution at 60Hz over Thunderbolt or 4K resolution at 60Hz over HDMI
- Up to two displays: One display with up to 5K resolution at 60Hz over Thunderbolt and one display with up to 8K resolution at 60Hz or 4K resolution at 240Hz over Thunderbolt or HDMI
more info on Apple page ...
'''
Therefore, single HD monitor will be easy. Times where normal human setup was limited in number of displays and their resolutions ended around m2, I think. Connecting $600 mini to multiple 5-6k displays is kind of crazy idea ;-)
Now, if your question is about color balance, it more depends on monitor and if macOS has description file for that monitor. Or if you know how to calibrate it.
For the sharpest image, you should use 4k monitor and set the resolution to HD, then each HD pixel is exactly 2x2 4k pixels and you get the sharpest image. Other resolutions system has to split pixels and that will not looks as good, typically.
Some people noted, that same monitor connected through different ports (USBC or HDMI) may look different. Explenation gets complicated, but it is worth trying.