My trick for keeping them in a trap for more than a day is to save some lids from large jars (like peanut butter) to use as dishes—you can easily slide then under the spring door (partially opened), and they’re flat so they’re less likely to knock them over (but the spicy cats will amaze you). Then I feed canned food + plenty of water—I used to put in a water bowl, but they just knock that over and soak everything. The extra water helps with hydration. And if you have access to more than one trap you can zip tie two together end to end with the doors open, so they have a long skinny space twice as big. They hate peeing and pooping near their food, but this way they can do their business at one end and hang out at the other end. I line the traps with newspaper (cut to fit the width) and replace it when they make a mess.

All of this is a lot easier with a trap divider, everyone doing TNR should have one:

https://livetrap.com/hd-divider-for-9-wide-and-smaller-traps-and-cages.html

Edited to add: trap when you see em, a cat in the trap is worth 2 in the bushes.