The option to "Erase all content and settings" does not appear, unless you are running an M-series Mac.
Which means that your MacBook Air is an Intel model. Apple switched to the M-series processor for the Macbook Air in 2020.
Your option now to clear out your files is to erase the drive, then reinstall macOS.
If you need any of those files that you have now, be sure to backup your drive before you erase...