I’m pretty sure the formularies (covered drugs in different categories) vary among Part D plans but have to verify that. When I picked my Part D plan three years ago I thought that my selected plan was better for high-tier drugs but again have to confirm. I seem to recall that all Part D plans have to cover a given number of drugs in each category but which ones and maybe copay amounts is up to them.
I swear to God that no one really knows everything until a claim is filed.
One thing I forgot to mention, I am also receiving Entyvio infusions (had 3 so far), and I have not had to pay a penny for those, Thank God.