can you have dual display with macbook air?

Yes, but to be precise we need what year yours is, for instance a 2020 MBA...

nd Display Support:Dual/Mirroring*2nd Max. Resolution:6016x3384 (6K)*

Details:*This model supports full native resolution on the interior display in addition to a single 6016x3384 (6K) display up to 60 Hz, a single 5120x2880 (5K) display up to 60 Hz, or as many as two external displays up to 4096x2304 (4K) up to 60 Hz.

This model has two Thunderbolt 3 ports. These two ports support charging the notebook, DisplayPort, Thunderbolt (up to 40 Gbps), and USB 3.1 Generation 2 (up to 10 Gbps).

▷ The MacBook Air supports one external display with up to 6K resolution at 60Hz. 

If you mean the M1 MacBook Air it only supports one external monitor.

MacBook Air - Technical Specifications - Apple

The hyperlink in my original response takes you directly to the source. 😉