It looks like you can structurally but how will you be finishing the top of the cabinets? if the plan was for crown molding, unless you add a strip on top of both the pantry and fridge cab it won't match up.

BTW, also recommended that all lighting be LED 4000K before choosing backsplash (and only once counters are in) and wall paint.

Good luck with the project!

Was not planning to add any molding

I think what you should do is add something on top that goes to the ceiling. they aren't difficult to DIY.

Quite a few different option you could do. Here are examples.

trim/molding and crown. all diff styles. just a simple extension trim w/simple crown would make it look finished a lot better.

this is the same kitchen. look how they tackled the open space w/the trim above the fridge. you don't have go this ornate. a simple trim would be fine.

you could also add an open cubbie (more on that below) to raise that height

this is basically how the step would look. (you need trim. )

but I think it looks better if you go to the ceiling.

you could do some add-on boxes. leave them open or put doors or glass on them.

this one looks cool for a more mcm look

you might think about redoing the cab on top of fridge for something higher. this just shows a DIY panel made from plywood

see how the wide trim above your cabinet would make this look better? they carried the trim/crown all the way around.

http://fishermanswifefurniture.blogspot.com/2013/08/diy-refrigerator-enclosure.html

I am wondering if I could bump just my wall cabinets up 2-3" while leaving the pantry and fridge cabinets the same? I don't see how I could extend the pantry and fridge cabinets up easily.

Bump them up if the bottom two shelves are still easily accessible. Don't worry about the space over the fridge. Either leave it open, conceal with filler or install an open shelf beneath the cabinet and use it for trays & cookie sheet storage.

I don't see a photo of the pantry cabinet. One possibility is to increase the toe kick area of just the pantry? Not a perfect solution but better than having staggered height up top where it will be very noticeable. Much less noticed at floor level. (Possibly add filler here to conceal the taller toe kick space?)

Depending on how tall your current fridge is, mounting the above fridge cabinet higher may be a good idea. Fridges have grown taller as time has gone by so you may be glad for the extra space should you need to replace it in the future.

**ETA...looks like you will need to replace the fridge & pantry side panels with taller ones. Or raise them somehow & fill at the bottom, possibly?

And, do I see a dryer hose connection there for an exhaust hood? Left side, first photo? If so, dryer vent hose is a no-no there.