I need to see the space but the first thing to come to mind is a wall with french doors to give a nice look and privacy and easily reversed down the rod if you sell.

How do you define ”private”?

- Do you need a locking door or noise control?

- Can the wall be glass or does it need to be a solid wall with a door?

I would make the room a bit smaller so the blue line (wall) is lined up with the entry opening rather than the narrower utility room opening.

I will need noise reduction. Partial privacy. Doesn’t need to be a full wall. No door needed. I was thinking bookcases.

if you need noise reduction add an area rug and upholstered furniture, tapestry on the wall...

With three openings, the cleanest way is to add a full-height glass wall or pocket/sliding doors along the blue line — you’ll keep light while gaining privacy. If you want something simpler, a built-in bookcase or half wall with doors works well as a visual and acoustic divider.

Room and board makes quality bookcases. Which - if you are thinking of using a bookcase as a room divider - you want it to look good on all sides. You would not get much of a privacy feel with all open back bookcases so you may wish to consider one with a back but then orient as such:

Real life example of a similar concept - this was custom in the 80’s in a Mies apartment in Chicago - floating the bookcases from the floor helped make the small spaces feel light and airy. And notice the art hung on the back of one of the units.