You could reduce the size of your vanity by moving the sink on the right down. A linen/storage cabinet could be installed in the leftover area. Good luck with your remodel!

https://www.houzz.com/hznb/photos/master-bathroom-smathers-0921-beach-style-bathroom-dallas-phvw-vp~182511205

Do you need two sinks? If not, one large sink in the middle will give you more storage while allowing you to shrink the vanity.

I would keep 2 sinks, moving the one on the right and either change the door to a pocket door or barn door. When both my spouse and I were working the bathroom in our previous home had 2 separate vanities and I really enjoyed having my own space and sink.

IMO the biggest vanity that fits for sure , bathrooms need storage and lots of it. I do not think a free standing tub will fit in the space where you want it. A FS tub needs a min of 12" all around and they are a PITA to get in and out of and to also add a tub filler . I steeer my clients toward a nice deep soaker tub either alcove or drop in . We have never had 2 sinks in 59 yrs and have never missed that but if ou are used to it then keep them. It also is a good idea here to post a to scale floor plan showing at least where the toilet is since moving a toilet is a big deal.

You may have electrical, plumbing or HVAC elements in the bulkhead, so investigate before ripping it out. Your new vanity…whatever length you decide on….will be more useful with three shallower drawers (rather than two deep drawers) so you can see what’s in each drawer. Deep drawers seem to get filled with too much stuff.

I have no idea how old you are, but we are putting on a new primary bathroom. We are using a little forward thinking by making everything accessible for future needs. A curbless shower, Accessible sinks, safe tiling etc.
just thought I’d throw that out there.
If done right, it can be very stylish and not institutional at all. This isn’t a project you’d want to do over again.