external drive for a 2019 macbook air Sonoma 14.7.4

you may be hard pressed to find one pre-formatted. additionally, if it is pre-formatted and claims to be "Mac ready", it likely is using a manufacturer's proprietary software that can stop working after macOS updates / upgrades. and anyways, formatting a drive is simple in any event.

please see Erase and reformat a storage device in Disk Utility on Mac - Apple Support

Joyously wrote:

Shopping for external drive for a 2019 macbook air Sonoma 14.7.4

Any brand name SSD will work. Make sure you use Disk Utility to format the SSD when you first connect it.

you're welcome.