Remove the drywall and frame it in with a header.

There are several sizes of doors sold (not custom). Have a contractor frame the opening such that a standard size door fits so you don't pay any more for the door than you have to. Try to get one that matches the other doors in the house. We have a 25 year old house and we were still able to get a match when we framed a door where there wasn't one before a couple years ago. It's not a difficult job for a contractor, but challenging for a DIYer without relevant skills.

Thank you for the response and suggestion!!!

Hire a contractor to create a frame for the door. I might even do a pocket door for this situation so the door doesn't swing into either the louvered doors or the vanity. If you have to have an electrician move the switches to accommodate the pocket door, do it.

You purchase a prehung door that matched your existing doors with the correct swing (into the room?) and have a contractor

• frame the wall to receive the door
• finish with drywall
• tape
• sand,
• prime
• repaint
• purchase and install matching hardware for the door

Make sure you have the clearance for a door to swing into the space

And if there isn’t any natural light in the bathroom space you might want to consider a door with frosted glass panels (more $ but getting some borrowed light into that space is nice).