Back in time (Eternals x reader)

After the emergence all the eternals went off and lived their own lives.
15 years later, y/n, the child of Druig and Makkari, lives a great life with both her parents and her aunt Thena. Their powers are time travel and the ability to read minds/ emotions (but not control them). Y/n has only learned to travel seconds and minutes but they want to do more.
What happens when y/n is practicing to time travel back years without anyone knowing? What happens when they go back in time to before the emergence and can't get back to present day?

Eternals x reader.
Using they/them pronouns (you can change them if you want)
There's not gonna be a love interest for the reader.