Wooden Patio on ground-What can I surround it with to avoid rot

What’s under it? That’s the key thing. If it’s sitting right on the ground it will rot.

Hopefully there is a layer of gravel under it, otherwise yes it would rot.

You can add a small amount of metal at the bottom of each leg that rests on the ground. An inexpensive fix that comes to mind is to use a soda can.....cut it so you have a lat piece, the create "rounds" large enough to place eneath the leg and bend the metal up around the leg. Sounds more complicated than it is. Also you might be able to locate some metal or rubber caps for your table legs at a home improement store.

You can seal it with sealant to protect from water

You can also talk to someone at your local hardware store. They should know what would work best in the area you are in.

Put it up on land scape ties they are treated and won’t rot

Have you applied wood stain to the wooden patio? If now, you should apply some stain. (To the top - this wouldn't help the bosom, though.)

I would put it up on some concrete blocks made for that purpose to level it and protect from rot. Also I would treat it with an oil-based deck stain like Olympia or Thompsons. https://www.lowes.com/pd/Common-7-in-x-11-in-x-11-in-Actual-7-125-in-x-10-375-in-x-10-375-in-Concrete-Deck-Block/50113084

I would also remove all grass from the area beneath the soon to be deck, add a layer of decomposed granite and a layer of landscape fabric to prevent weed growth.

You’ll need to raise the wood up off the ground at least by a little bit. Or if I read right, some separation between the concrete and wood. Please don’t add metal anywhere, it will rust or corrode causing all sorts of other issues.