Simultaneously supports full native resolution on the built-in display at 1 billion colors and:
Up to two external displays with up to 6K resolution at 60Hz over Thunderbolt, or one external display with up to 6K resolution at 60Hz over Thunderbolt and one external display with up to 4K resolution at 144Hz over HDMI
One external display supported at 8K resolution at 60Hz or one external display at 4K resolution at 240Hz over HDMI"
"M4 and M4 Pro
Simultaneously supports full native resolution on the built-in display at 1 billion colors and:
Up to two external displays with up to 6K resolution at 60Hz over Thunderbolt, or one external display with up to 6K resolution at 60Hz over Thunderbolt and one external display with up to 4K resolution at 144Hz over HDMI
One external display supported at 8K resolution at 60Hz or one external display at 4K resolution at 240Hz over HDMI"