When setting an Experiment Url, can I use wildcards?
That is what the regex matches are for (or substring match)
A regular expression like this will match any URL that contains "domain.com/user/" where there is at least one character following /user:
matches - http://www.domain.com/user/myaccount
does not match - http://www.domain.com/user/
You could also set up a "substring match" that will match any URL that contains "domain.com/user":
Be sure to read/watch this help article for a nifty video and examples of the different ways to set up URL targetin: