Not sure if I'm following you 100%, but I'll take a crack at it.
Are you asking if the NEC required disconnect for the spa can be buried?
If so, the answer is no. It must be at least 5' from the spa water and within sightline to be compliant with NEC (Assuming you have to conform to NEC).
I'd settle on a spa before going too far with your wiring. Once you choose a spa, that'll tell you what you need for wiring-
Spas can be 120V or 220V, can be wired for many different amperages, some come with the required GFI breakers built in, many others do not.
You can do your own wiring, if your area allows homeowners to do their own wiring.
Most likely if they do, you'll need permits and inspections. If you're not familiar with pool and spa wiring, consider hiring a pro- this is not a good learners project.
In my area, you can wire you own dwelling if it's owner occupied. Businesses and rental must be done by a licensed electrician.
Rules in your area may vary- consult with whoever regulates the electric inspections in your area.