If you got him 3 days ago its prob coz he is still stressed. Make sure u r giving him soaks and there is no harm in giving him a baby food soak aswell.
Is he drinking anything?
My tortoise Vodka didn't eat for a week straight when I got her. Give your guy time, and keep offering food. Don't mess with him too much and just do regular husbandry like cleaning out water bowl etc. Keep offering food, when he settles he will eat. Torts aren't like dogs and cats who will eat the first two days, these guys will hold out till they feel secure. Soaking every other day is good for him too, it will keep him hydrated.
My tortoise did the same thing when I first got her. She had to settle in before she became calm and comfortable to eat. After a couple days, though, she was fine.
Also, it helps to spend time with and bond with your tortoise because it might start to associate food and safety with your scent.
~Happy Owner of a Russian Tortoise [HEAVY BLACK HEART][TURTLE]
Also, collard greens, kale, and mustard greens are good food choices for your tortoise.
~Happy Owner of a Russian Tortoise [HEAVY BLACK HEART][TURTLE]