I don't think you can fit a big walk in but you can do another reach in. I wouldn't sacrifice a bedroom for closet space. Bedrooms add more value to a home than closets.

You can shrink down the secondary to the same size as the other and move the entrance. This will allow the current primary reach in to deepen and allow you to move the entrance to the primary bedroom. Then you can shrink it down 2ft to add another reach in closet.

(please excuse the crude sketch! I'm on my phone without access to my computer.)

You have to walk through a bathroom to get to the bedroom? I’d fix that first.

How do you get into the bedroom?
I would add a door from the hallway and enlarge the walk-inn.
Take away existing closet and you can have a make-up nook or chair, chest of drawers or whatever you fancy in that little nook.

A cleaner pic of my idea:

It appears all 3 bedrooms must share a bath? and that’s why you are entering the master bedroom through the bath. I think you are wasting space in the hallway. And also with the doorways.

are you working with an architect?

I might consider this sort of basic layout. Narrow the hallway at the stair but make it wider at the top. Access the bath from the hall. It would take space to have a second entry via the master. Then you have a place for an inefficient walk in closet. Or you may get a nice reach in if you turn the bath 90 degrees.

but I think a person with time and talent could do better.

I agree that original layout needs to be worked on first. What do you mean by a good sized closet . How do you propose to move a bedroom to the main floor , maybe show that too. These bedrooms are already small so taking space from any of them is IMO not realistic. You need to address that impossible entry to the main bedroom first . Get an interior designer to work on that.That bathroom needs to be accessible to all the bedrooms from the hall and IMO not at all ideal for a master bath.

Thank you all for your comments, here’s an idea of what I was thinking. (Clearly not a professional here haha) the stars represent doors (the master door was left out of the original plan for some reason but there is an entry from the hallway)

Is 9x6 foot walk in closet large an average size? any thoughts on ensuite layout? We are adding another bathroom to the main floor for kids to use, leaving the ensuite for me (This home is a backsplit layout)

Your closets don’t appear to be “walk-in” size. I would extend all the closet doors to full-width sliders and you can have full access with a “reach-in” design.

Sorry I should clarify I’m looking to make space for one walk in closet for the master bedroom. The other closets are fine as is

Before you start moving doors and walls, you need to determine your roof structure, e.g. trusses or stick-built? You also need to find the chases for plumbing and ductwork (if any). Typically the Linen back/side wall houses stuff. Your room sizes need to maintain a certain proportion - you have a small footprint - so for Master try to keep a 13'or14' X no less than 11'. For kids 12'x10' or 11'x9'. Try to make an accurate representation of the plan to scale. Consider what altering room layouts do to windows, and if moving windows how that affects elevations.