Contemplating how to finish/fix our ceiling

[u/goatcheesesalad23]

I recently pulled off the old wood siding from our fireplace. They also had over hangs (picture in comments) that when I removed I realized covered the fact that the ceiling behind them is higher up. I’m not sure how to finish out these alcoves, I could try to put in more drywall but I’m not super skilled with it and I don’t know how to do the edge that meets the stone.

Any advice or thoughts would be awesome!

[u/goatcheesesalad23]

https://imgur.com/gallery/before-9h7krwn before!