Have it checked by a vet. Last stray we took in had five different species of parasitic worms and a bacterial infection - all transmittable to humans at one risk level or another. And fleas. And ticks. Then there are diseases peculiar to cats - and usually fatal, like feline leukemia. Yours may not have been outside to get infected, but who knows. Ans: the vet.
Outside can be a dangerous place for small animals. Here, cats routinely let "out" are routinely eaten by coyotes (suburbs of Cleveland), feral dogs, and raccoons + they pick up all sorts of diseases, many fatal. If you let the cat roam, expect enhanced vet bills and/or a significantly shortened life-span. I have seen dogs and coyotes trotting across the fields with cats in their jaws. Cats evolved for Ohio are, in order of power, Bobcats, Lynx, and Puma. Not F. domesticus. Also, cats let out bring back "gifts" - dead baby rabbits and birds and snakes of all ages. In fact, they can make a big dent in bird populations - esp ground-nesting species. Nature is red in fang and claw.
Get a cat box. Put it somewhere as inoffensive as possible. Garage? Utility room? Enclosed porch? Places that sell stock feed (think hay and rabbit and goat pellets) often sell large bags of compressed pine "bedding." It is significantly cheaper that "cat litter" or "feline pine" from Walmart. It makes excellent material for the cat box. No dust and less stink. Get a pooper scooper to remove lumpy stuff. The pine litter is flushable, but the bulk makes good material to fill in low spots. In a short time, it looks like the area it covered (just ground wood).
If the cat is going to risk the outside, it needs all its claws for the last ditch climb to survive or to sell its life dearly. If it an inside only critter, consider removal of front claws. Some think that declawing is terrible. Cats think clawing on stuff with their front claws is necessary - because it is necessary to remove claw layers as they grow out. Some cats can learn to use only a scratch post. Others just will claw on the sofa or kitchen cabinets.
Cats love cardboard boxes - better than most cat habitats you can buy.
What do they like to play with? Soda bottle caps (cat hockey). Crumpled balls of paper. Not string or dental floss. They like to swallow it, often leading to surgery or death.
They like to eat many house plants - esp anything grasslike or fernlike. They do not like orchids.
Get them neutered or spayed. Females howl - loudly - for days periodically, spray, and have elevated medical problems. Males spray (PHEW!). All to be avoided. Costs for these services vary tremendously - like by an order of magnitude. Folks at local no-kill shelters are a source of good advice about where to go.
You just saved a life. Now you are responsible. Any traditional Chinese person can explain.
Bless you.
We have five now - all strays. Kids are gone so there is room.