One thing I like to do is set up a vine or two (or rope) in my cage that leads out and is wrapped slightly around a tree (ficus or hibiscus). My Cham was never handled and still is wary about it, so it all works out by letting him come out at his leisure. He hangs out on the tree while I clean his cage/do rearrangements.
Now I will say, I set this up for him daily before he got used to the idea of coming out. It took him about 3 days until he finally did decide to come out.
Now when I set it up, he climbs out immediately!
Pics: two variations of what I’ve done. 1st is a vine leading to a hibiscus. 2nd is what I’ve developed over time. The gist for me is just get a safe plant, set it up higher than his cage, attach something he can climb on from cage to plant, and the magic happens!