What a wonderful blank slate!
I really encourage you not to turn it back into grass desert. A grass monoculture (aka "lawn") produces nothing, supports no life, requires a lot of tending, and is the most boring thing you can plant.
Start by thinking about what you would like to do and see back there. I don't know if this is all of your property. Would you like to have a patio, cooking area, eating area? A gazebo for shady hanging out? A fire pit for bonfires, roasting marshmallows, etc? Personally I think every yard should have some kind of water feature. That can be as minimal as birdbaths, but especially with so much space a little pond would be really nice. You can buy the pre-formed ones or flexible pond liners.
Yes, absolutely some raised beds for herbs and veggies. Start with just a few and see how it goes. If you turn out to love growing veggies you can always add more later. But besides veggies, what else would you love for your property to produce? How about some fruit trees? Or berry bushes along the fence line? Berry bushes will bring honeybees, butterflies, birds, and other wild life to your yard. Blueberries, raspberries, elderberry, grapes, gooseberries, serviceberries ....
Do you have kids? If so, you will want a kids play area.
What about a shed for lawn and garden equipment? Compost bins?
Start by drawing ideas out on paper. Once you have some of it in mind, start with hardscaping - patios, paths, buildings, pond. After that stuff is in place, it will get clearer what you want to do with what is left.
Look for inspiration pictures.
Remember not to do everything in straight lines:
and with a flat back yard, some level change gives a relief to the eyes:
when you look at pictures often you will see a lot that is grand and complicated and expensive. But if you think about what you like about it, often you can find ways to keep that, just in smaller, simpler version.
Remember that this will be the work of several seasons and be patient with yourself!
PS about simple, inexpensive, easy to build raised beds. Here's a thread where I posted pictures of my current raised beds of landscape timbers and one of one of the beds of 4x4's that I made at my previous house: https://www.helpfulgardener.com/forum/vi ... ds#p383540
I built four 8x4 raised beds of landscape timbers for $120 total. They are just stacked and held together with steel rebar pounded down through (drill holes first!).