Eliminate the tight “U” shaped corner.

What do you plan to do at the air return/supply?

@Mark Bischak, Architect its The same on the Opposite end but longer, meaning there’s room to crown it. I’d like to keep it the same on the problem side. I can always reduce the register in size. Maybe I can keep the register there and just keep that “problem side” empty then start the crown as usual After the register? How would you elimI ate the U?

Skip the inappropriately large crown. Flush out the drywall. Accept that your home is a bit more contemporary than traditional, and roll with it. A home without casings does not use ginormous crown. Or any crown.

"its The same on the Opposite end"

Eliminate them both.

"reduce the register in size."

You do not understand the ramifications of that.

"How would you elimI ate the U?"

Wood blocking and drywall.

I'd get a hunk of MDF, painted to match your crown. mount it in the U flush with the bottom of the crown, and filling the U. then run your crown right across the U.

Or just take it down an be happy like you did! :)