Turn your spreadsheet into a database with examples for querying, inserting, updating, and deleting via API. In this guide. I’ll also explore the limitations of Google Sheets, including scalability, and where it makes sense to start looking at more complex alternatives.
Whilst not directly Google Apps Script related this post from Jacob Lee (Co-founder Autocode) provides lots of useful advice and tips on using Google Sheets as a database. The post also does an excellent job of highlighting the hard limits as well as usability issues before you hit those limits.