With the dimensions of the new closet space, try the website for The Container Store to do a closet layout. Especially their Elfa system. Easy to use and has lots of options for using drawers and hanging needs.

This is a master bedroom with two beds.........? Personal reasons but a curiosity. What else in the room please?

You don't just "knock down" a fireplace wall. Venting should be removed, /closed and there are codes.

You need more info as to closet. These are personal to your ow clothes and dress style.