Does Anvil recognize datetime.timedelta?

Yes, Anvil has full support for datetime.timedelta. The problem you’re seeing is because you’ve imported the datetime and timedelta classes directly, so you can refer to them directly:

from datetime import datetime, timedelta

today = datetime.today()
t_delta = timedelta(days=7)

Alternatively, just import the datetime package:

import datetime

today = datetime.datetime.today()
t_delta = datetime.timedelta(days=7)

Hope that helps!