The third picture doesn’t have the correct measurements, just a layout.

I fiqured out that you want to convert living room to a master suite. 1st issue is bathroom is too narrow. The minimum size for a 3-piece bathroom (typically a ¾ bath with a toilet, sink, and shower) is 26 to 30 square feet (often built in a compact 5' × 6' or 6' × 6' footprint). If your 3-piece layout includes a full bathtub instead of a stand-up shower, the minimum size increases to 36 to 40 square feet (commonly designed as a 5' × 8' room).you need 5 feet minimum. Your allocating alot of space to the study- how will you use? how many people will be there? if your the only one to use it 99 percent of the time it could be significantly smaller. . Are you converting this home into a two family?

Nice use of space if you only need one living room. If you cant make the powder room work, maybe you can put a powderroom in the laundry room. Laundry room looks big enough to divide. looks like you know what you want. Are you moving elders in or just yourself downstairs?

Estimated size for splitting the 7.5 x 7.5 bath:
en-suite ~. 9.5’ x 4.5’ =42.75’ sq ft w/ only a shower. Extends longer than the original layout. See pic 2 or 3.
The powder room would be ~ 3’x 5’ or 3’ x 7.5’ =15 - 21 sq ft. Not exact measurements, w/walls but the larger bath would exceed the req. listed in comment above.
2-3 users in the study max.
This is for a single family residence.
Main concern is for splitting the size to the right of bath and staircase. I’m trying to make the size of bathroom, walk-in, study all fit in the remaining space 15’ x 29’ and avoid placing walls in front of the existing windows. I think the smallest for study is ~ 10 x 15, just not sure how
tight that would feel. Considering making the closet into an angle or l shaped, irregular size.

Before you move any walls, I'd check where the plumbing stack runs. If the existing 7'5" x 7'5" bath sits on a wall you can share, putting the en-suite and powder room back to back on that same wet wall will cost far less than running new lines across the floor. I'd also let the walk-in closet sit between the bedroom and the study, since closets are a great sound and privacy buffer. And agree the study can be smaller than you think: a 6' x 8' nook with a window is plenty for one person.

Edit: just saw you mentioned the study is for 2–3 people, so ignore my 6' x 8' suggestion. Your 10' x 15' minimum sounds right.