I found the biggest ant I’ve ever seen in Costa Rica…it was a trap jaw ant, and it was (unfortunately) hanging out on a vine right at eye level on the trail. I have played with (smaller) trap jaw ants before in the lab. If you give them a little fruit fly, the moment it touches the trigger sensitive hairs between their mandibles (which are open at rest), their jaws snap shut with so much force that it flings their bodies into the air.
Here’s a video someone posted of that (it’s kinda hilarious):
And here is the ant I saw in Costa Rica! It must have at least been 2 cm.
Before you ask, no I did not test those jaws.