Having what amounts to a huge carport built, basically a 65x36 tunnel to provide overhead & side protection for RV, boat, trucks and cars. Both ends completely open for drive-thru convenience. Want to take one corner and build a 12x12 or so storage/tool shed but need to make a raised floor for it, something 10-12" high. With the cost of concrete don't think a 10-12" slab is viable. Thinking a 2x8 or 2x10 frame floor sitting on cinder blocks might do it. If I go with a raised frame floor like that, what can I do to keep termites out?

Recommendations?

just use pressure treated for the joist framing, plywood and plates. termites won't touch treated wood.

If you poured concrete you don't have to pour it 12" deep. You can fill it with 6"-8" of sand, gravel or dirt.

Both above are correct. I assume you're having the carport poured and just want a higher level area for a tool shed? If so, they can frame that and fill it accordingly. Whether you pour concrete, or frame something with pressure treated lumber, I strongly suggest you consider making the finished floor inside the shed no higher than 10 inches above grade (of where you're stepping from). The reason is natural human comfort and coordination in taking a step up. This is even more true when carrying objects. 9 inches would be even better. As you go above 9, the human tendency is to catch a toe on the higher platform and stumble. There's a low number recommendation as well, but I don't recall it for sure. (It may be 6 inches - step elevations that are "too small" are also unnatural to our bodies.)

Also, if you fill and pour, be sure they compact the fill material so the floor slab won't be as prone to crack from fill settling. Also, insist on a vapor barrier for the slab portion where the shed will be.