Agreed, making sure zoning will allow you to have the 2 horses is primary.
After that you need to find out restrictions on adding outbuildings.
You may be limited to a pasture shelter.
If so, check Horizon Structures as they are not considered permanent & could give you a shedrow-type structure that would suit your purposes.
I keep 3 - horse, piny & mini - on less than 5ac (my total lot) inuding a 46X36 center aisle pole barn & attached 60X120 indoor.
My “big” pasture is just under 2ac, smaller is 1/2ac, sacrifice area surrounds the front of the barn & back of stalls & opens to both fields.
Nobody could call my pastures *lush", but with grass in, hay consumption drops dramatically.
I do feed hay year-round, but right now I split a flake between horse & pony, mini gets a handful.
All are fat as ticks (in a good way).