Does a MacBook Air USB-C work with any monitor?

Yes, as long as the monitor has a USB-C port or DisplayPort input. Every MacBook Air since 2018 supports DisplayPort alternate mode over USB-C, so you can use a direct USB-C connection or a USB-C to HDMI adapter for HDMI-only monitors. Just note this only applies to 2018 and newer models—older wedge-shaped MacBook Airs lack USB-C.