Hey there @SimonM1, thanks for reaching out to us.
Currently, there's no option for you to request to expire your password, but you can reset it following these steps.
Also, although you don't get a notification as to when your password is going to expire, you'll see an error the next time you try to sign in.
You can find more info about expired passwords here.
I hope this helps, but let me know if you have any other questions!