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
Cats often hide close by. Check with all your neighbors, around the block & across the street. Knock on doors, and/or distribute notes or fliers with picture & contact info (I printed them 4 to a page, cut up & taped them to front doors). Last year my old cat went missing for 10 days; turns out she was trapped in a neighbor’s garage only two doors away! Your pet is very likely nearby. You may even try putting the litter box or bedding outside, so your cat can smell it. Also, keep checking with nearby vets, and your local shelters (I left or emailed picture-fliers there too). Check daily! Best of luck.