Is it possible that alters remained inactive?

I don't know how to say this properly. So I (17 trans Fem) have been looking into Tulpamancy, but recently a friend that I met, who is a plural system, got me questioning on if I've been a system with alters that were inactive or something like that. I met this friend by a reference from another friend on discord. When we talked she had me done meditation type thing that was supposed to bring out an alter, and I felt different. I was conscious but I felt wrong, I was looking around my room like I didn't recognize it. Apparently my voice sounded different from when we started the call and after the meditation. So I'm asking, Is it possible that a system has been inactive for a long time and can be activated?