Airtable’s built-in automatons let you run an action in Airtable when you create a new row at the bottom of a Google Sheets spreadsheet.

But to watch existing Google Sheet rows/cells for changes — and to perform more advanced automations based on those changes — you would need to use an external automation tool like Integromat, which has full Google Sheets support, including watching for new rows created at the bottom of a spreadsheet.

(Note that I am an Airtable Consultant and a Registered Integromat Partner, and that link contains my personal referral code.)