Autofill a property field based on another property field

I have a ‘Date’ (21-04-2026) property field and a ‘Year’ property field (2026). (Note: I need to have them separately because - I don’t always know a precise date, but I always enter year in the year field).

When I select a date, how can I autofill the year? I create many notes every day so it will be helpful.

Auto fill a property field based on another property field