If your cat is indoor/outdoor (or outdoor-only), you may have noticed when it first ventured out that it stayed quite close to the door and cautiously started to explore (and mark) its territory. In subsequent outings, it gradually expanded its territory as it found new comfortable resting places. What you may not have noticed is the bounding of its territory by the markings of other cats. Whenever it encountered consistent markings, i.e., another cat clearly had claims on the territory, your cat backed off, left some "neutral territory", and clearly marked the boundary of its territory. (If your cat's territory eventually proved uncomfortably small, the position of that boundary (or its very existence) may later have been negotiated between the two cats.)
Once your cat has defined its territory, that's where it will tend to stay. It's comfortable there — it has its favorite resting and sleeping places and it knows when and where you'll feed it. Unneutered males will roam those neutral territories, but females and neutered males almost never will — at least by choice. However, the cat can be frightened out of its territory — by another animal chasing it, by startling activity between it and its normal hiding places, etc. When that happens, it will run away from the threat until it finds a new hiding place where it feels safe — its fear of the immediate threat overriding its fear of (or respect for) other cats' territories.
At that point it's "lost" — but it's not really. The cat is in unfamiliar territory — but it instinctively understands the nature of "territories", has had some actual outdoor experience with them and knows the general direction of "home". When it calms down — which may take some time (the fear of the threat is gone, but the fear of being on unfamiliar ground remains) — it will cautiously start scouting out its surrounds (just as it did when you first let it venture outside).
It will first seek neutral territory — and a safe hiding spot in that territory. From there, it will scout out the neutral pathway in the general direction of home — and find another safe hiding spot closer to home. This process repeats, slowly and cautiously, and probably only at night, as it works its way back home. It may take days for the cat to return — even though it may never have been more than several houses away. But it will return eventually (barring unfortunate encounters with predators, vehicles, well-meaning humans whot "rescue" it, etc.).
As you might surmise from the above, the indoor-only cat is less well equipped to dealing with being lost than the outdoor cat. Its territorial instincts are alive and well — but is has no outdoor territory of its own and no actual experience with outdoor territories. When an indoor cat "escapes" — perhaps through an open window in pursuit of a chipmunk — perhaps through an opening door accompanied by your attempt to stop it — it will run some distance without thinking. But suddenly it will realize that it's in unknown territory — fear sets in — and it will dash for the nearest hiding place it can see. This despite the fact that you or your house may be clearly visible — may even be closer than the hiding place. The cat is terrified — and its instincts are telling it to hide!
Wherever it found to hide, you can be quite certain it will stay there until nightfall. Its fear is greater than the outdoor cat's because the experience is totally new to it. After dark it may start cautiously exploring its immediate surrounds — just as the outdoor cat did when it first ventured outside. But it has no sense of "home" — all of its markings are in the house, not outside. Its instincts are telling it only to find a safer hiding place — but that new hiding place is as likely to be farther away from home as it is to be nearer. The indoor-only cat may eventually return on its own — traces of your scent are outside, if not the cat's — but it's much less certain than it was for the outdoor cat.
Start looking as quickly as possible — especially for the indoor cat that has just escaped. The cat is almost certainly very close at hand.
Don't give up. Keep looking for at least a couple of months. It can take that long for the cat to find its way home — and even a declawed cat can find, hunt and scrounge enough food to survive.
Although any cat is capable of getting lost, there are things you can do now to minimize the chance and to facilitate its return.