The M4 Pro model is able to support up to three 6K displays at 60Hz over Thunderbolt or HDMI, an improvement over the previous M3 Pro model. Apple's M4 Pro chip alternatively supports one display at 6K resolution over 60Hz and a second display at 8K resolution at 60Hz or 4K resolution at 240Hz.
Meanwhile, the M4 Max model supports up to three external displays with 6K resolution at 60Hz over Thunderbolt and one external display with up to 4K resolution at 144Hz over HDMI, or up to two external displays with 6K resolution at 60Hz over Thunderbolt and one external display with up to 8K resolution at 60Hz or one external display with 4K resolution at 240Hz over HDMI.