Just look for the ratio in the specs for any you find on the market.
A 1:1 will do exactly what you described above. 1 inch away covers a one inch area, and 5 feet a five foot area.
But with a 1:1 you want it to be as close as possible or you'll get reading distortions from ambient air temps.
You shouldn't need anything expensive or extremely tight in focus if it's just for checking hot spots in an animals cage. For engine work and electronics, sure