Do you plan to use it for seating? If so, remove the gravel and put down pavers. If you don't plant it up. I'd put a climbing rose or a grapevine on your arbor. Kiwis are pretty, too. You need a male for pollination.

Your space has four levels. I'd bring the three other than the deck up to the level of the walkway. I'd use whatever paver is in the firepit area for that now single level. I'd make it more accessible by removing the railing on that side of the deck and having steps all along the now open side of the deck. 2 steps look OK.

I do not plan to use it for seating, I have 3 patios around my home, that already all have seating. The fireplace area, the area above it, and a large 30x40 patio on the front side of the home.

This area is also sloped, the gravel just makes it appear more level, because of water shedding, so this area is built to help with drainage around the home.

I would rather try to think of another use for it aside from just yet another seating area, some nature idea would be nice, but have zero idea of any ideas for it, should I put walls up around it, make some sort of trellis wall and turn it into a nature area. No idea hoping to find some photos for inspiration..

Bringing the fireplace level up could be possible, but would be very costly I would think, almost 3 feet high to get it to be level there is also a lot of drainage pipes already in the fireplace area for water shedding.

Be roughly 15 wide, 12 long, and 3 feet high to backfill in that much, and re routing the underground pipes too bring them up higher.

Like the idea though!

It looks like you are somewhere it rains. Ohio? Gravel is a serious PITA anywhere that isn't arid because weeds love it.

Either plant it up, or get rid of it.

A small orchard with dwarf fruit trees? You could keep the gravel for them. The gravel looks like the original grade. You could get add more flagstone for the path to the area, easier to walk on. Easy to blow clean.

The structure could be removed... was for a swing I guess.

Turning it into a garden area with a tree to provide for the other patios and flowers/small shrubs would be nice. The tree should be closer to the back of patio, not near the house.

Yes, located in Midwest, southern IN, decent amount of rain. What do you suggest instead of rock? I do not like mulch, having to replenish it each year, feel like rocks are less maintenance (for me) anyways when I just spray a little weed control on the rocks during spring.

Yes, a tree would be nice to add in, what sort of tree would be best? I like the idea of turning it into a nature type area, just have no clue where to even start with. What shrubs, plants, etc. Just trying to get a plan for spring

Start with a small tree--redbud, Cornus kousa, Amelanchier, Viburnum prunifolium, etc. A good nursery should be able to help.

Where would you recommend planting it?