Not like the custom content but like the actual clothes they originally came with. I don't if I'm making sense right now, its like 12 mins to 7 in the morning. XD
You have to mail them the clothing you want them to wear. They won't always wear what you send them. You might have to send letters multiple times before they wear the clothes.
If you want them to wear their original clothing, you can complain to Isabelle that they're dressing inappropriately and they'll change their shirt. Sometimes this doesn't work for some reason.
If I complain to isabelle the villagers will wearn a stupid gym tee, not their original clothing. What works best for me is that I have the shirt I want them to wear in my inventory and just talk to them a lot
I'd report her to Isabelle first so she wears a default t-shirt, and then mail her the shirt you want her to wear.
changing the shirt models in Able sisters to Umbrella or dress models will make sure your villagers don't change out of their clothing so easily ^_^