You’re taking about a built in feature of gmail. Check this out. https://gizmodo.com/how-to-use-the-infinite-number-of-email-addresses-gmail-1609458192?_gl=1*13pcy34*_ga*YW1wLV9sY3VySnFjVXRrdVM1UVhPclM5bUc5RnJra1VBbEdfakdsMlBaTEEzOTBzQmlqNkpELVgzTGl3YjBWWHVlUDA.