In a pair of support documents, Apple has listed various external display combinations that can be used with the new Mac Studio and Mac Pro. For example, both Macs support up to eight 4K displays at 60Hz when configured with the M2 Ultra chip.
The new Mac Studio has an HDMI 2.1 port, and the new Mac Pro has two. These ports each support an 8K display at 60Hz, or a 4K display at 240Hz. Apple says the M2 Ultra chip also supports up to six Pro Display XDRs.
Read more at MacRumors.com