is there a downloadable manual for the 13 in macbook air?

Some online instructions are like manuals. To save them

offline, as PDF you may test: 'Save as PDF' from Printer

options menu. Could vary depending on browser used.

Larger multiple-page 'user guides' maybe ideal saved as PDF.

Those often are general topic range, includes several articles.

• macOS User Guide [Table of Contents] - Apple Support

https://support.apple.com/guide/mac-help/toc

• Keychain Access User Guide (Table of Contents) - Apple Support

https://support.apple.com/guide/keychain-access/toc

Web-based content often changes without notice, &/or evaporates.

An obvious advantage in Apple "Books" with iDevices. Portability.

Online articles from Apple Support have seen inclusion of M1 info.

Several refer to 'Intel-based' Mac and M1 'Apple Silicon' -- together.

Apple - Support - Manuals