If he is indoor only I will add steps. Need to crack open the garage door or other access 24/7 to let him come back inside ASAP. Definitely close by and I’m sure has taken cover for warmth under a shed or crawl space for example. Need to get fliers. They always try to return to the exit they went usually and night and especially between 4-7 am. Keep an eye on that door and focus on luring with soft familiar calls from that door as often as possible. If you have an attached garage crack that just a bit with scent items inside and just outside both doors (garage and door he went out). Scent items are worn clothes of family, his bedding, your slept on sheets, litter box etc. They can hide so well nearby that it seems as though they have vanished. It’s a way of protecting themselves. Flier door to door in a 7 house radius of your home. That’s typically where they stay for quite some time. Even months. Baby monitor outside the door he escaped is always helpful to hear meows or scratching. Also see site for steps to finding an indoor only cat. There are also steps to outdoor access. Pet-trackerinc.org
Sherry Neal One of ours crawled into a drawer when I was putting laundry away. We thought she had gotten out, but found her 36 hours later when I opened the drawer.
BUT, do put his litter box on your porch, along with some clothing you have worn and not washed. They have great senses of smell, and will come to it. Leave a window cracked nearby so that you can hear him. Cats usually don’t go very far, and will hide. They often come out around dusk or daybreak when there aren’t people around. Look around the neighborhood at dark with a flashlight. Look under cars and bushes. Post pictures of him all over the neighborhood. Talk to neighbors and ask them to check sheds and garages. Post pictures in nearby vets’ offices. GO to animal control and the spca. Leave pictures there, too. If you put food out, stay close by because it might also attract other animals that would scare him. I hope you find him.