tracking – Should userId be established in each Google Analytics session?

When using the user identification feature in Google Analytics, userId Do you need to configure each session to link sessions with the same user?

I see that there is a session unification option that connects page views from before userId is configured in the same session, but could not find documentation on whether multiple sessions are unified to the same user without configuring userId in each session

For example, a new user browses the entire site, then submits a form, after which a unique identification is generated and userId It is established.

The next day, the same user returns to the site without taking any action to identify them exclusively.

Will the second session be linked to the same user when reporting the user in Google Analytics?