How to handle 1 inch gap between bathtub tile and drywall?
There is a 1" quarter round ceramic available. Local home centers here stock it.

You could also rip down bullnose edging.

If you're bold enough, you could try to mix up some colored sanded grout on the stiff side, and try to run a chamferred edge detail.

Lastly, although it might be ugly, you could install vinyl quarter round.