Yes.
Endogenic systems exist, and they only differ in the means by which they occur from traumagenic ones.
Compartmentalization and dissociation are incredibly common things to do as a response to trauma, which are how systems happen to come to be. This means that anyone good enough at the two (which can be practiced) can, alone or with help, form system members - headmates, tulpas, anything you want to call them - without experiencing trauma.
Again, the only thing that differs are the means by which plurality is achieved, and in some cases (but for any way to get there) the intentionality of doing so.
Daryl Talks Games mentions tulpas in the "What Artificial Romance Does To People" video (which, be warned, does reference Harry Potter, which made us bounce off it. We were shown by a friend the following) and quotes researchers saying:
"The impact of trauma and the resulting function-imparing symptoms are what make Dissociative Identity Disorder a disorder, not the plurality itself."
In short? Yes, you can be plural.
