how do i stream 4k from macbook air to my 4k capable tv

The M4 MBAir models do not have an HDMI port. They have USB-C ports that support Thunderbolt 4, USB4, charging and Displayport 1.4.

You would need a USB-C to Displayport adapter and a DP cable to connect to your TV. However, if your TV does not have a DP input, you could use a Displayport-to-HDMI cable to connect from the adapter to one of the TV's HDMI inputs.

Airplay 2 supports 4K video streaming but screen mirroring is limited to 1080p. And your TV would have to support Airplay 2.

I'd cable the connection instead of taking chances with Airplay.

How you connect the Mac to your TV depends on the type of TV, as different TVs support different methods of connecting. Try consulting your TV’s documentation.

I probably should have clarified: I was asking for the TV model. As for which option works better, that can vary between different TV models, so you should probably ask the company who made your TV.