It is a very good idea to change your password to your email account immediately.

That's a good rule of thumb when anything you feel is suspicious occurs.

Not exactly your situation but shows you some stuff to check.

https://support.google.com/accounts/answer/6063333?hl=en

there's a "manage your account" or some such where it shows you which devices have access to your account. Delete all that are not yours.

Had such an event but it was in an email since I don't do internet on my phone. But check devices before or when you change your password.

Besides, it's telling you to check an email. Obviously wants you to click a link in said email. Delete the email too. Don't bother reading it. Seriously, these are huge clues, just don't fall for them and we'll all be fine

Didn't receive said email? Good. Anything that comes via text or email that seems off just delete and ignore.