Yeah, Dgraph can’t create DTypes based on user usage. That would require some dark magic (with AI?). So, you have to define your mutations manually.
I think you won’t see this cuz it is a system predicate - so you can modify it. You can see tho, via query. e.g:
{
q(func: eq(something, "else")) {
name
<dgraph.type>
}
}