How many external displays can the M3 MacBook Air support with the lid closed?

Regarding the MacBook Air: Two, but only if you close the laptop lid. With the lid open, it supports a single external display up to 6K at 60Hz. In clamshell mode, you can run two external displays — one up to 6K at 60Hz and another up to 5K at 60Hz. This is because the M3 chip can only drive three displays total (including the built-in screen), so closing the lid frees up an external slot.