I want to do a thing where I write separate novels using each of these three subgenres; young adult, new adult, and adult.
So, if I was writing fantasy books, I'd write a YA fantasy book, new adult fantasy, and an adult fantasy book.
I already have a YA fantasy series; next up will be new adult and adult fantasy. None will be connected.
I'd do the same if I was writing sci-fi, horror, adventure, paranormal, etc. It's basically just, like, telling different stories in the same genre and using different characters of different ages.
I think it's pretty cool.