Where is the BOOKLET option in Print?

Not a lot of information to go on with your post.

The "Booklet" option for printing is not directly available in macOS's built-in Print dialog, as macOS does not natively support booklet printing. This, most likely, was an printer option and would depend on the printer driver being compatible with the version of macOS running on your MacBook Air.

Some printers (like those from Brother, HP, and Canon) include booklet printing as a feature within their printer driver settings.

Ref: Writing an effective Apple Support Communities question