Are there ways to hide the password from yourself for a certain time?

Question

Passwords

Hello, so far the only solution I see is to use the letter to the future service. Please tell me if you know something similar, but in the form of an application on a phone or PC, well, or a site where access to data will open only after a certain time, which he himself installed.

Answer 1

And who will prevent you from changing the date on the device for the future?
Or you don't need a failsafe?