There isn’t a way to immediately “force” one of your villagers to wear a shirt of your choosing, however there are some methods that you can try!
1. Send your villager the tshirt through the mail. This is not 100% guaranteed to work, but if you are persistent your villager is bound to eventually wear it! You can also opt to send the shirt before 5pm and save your game at 4:59pm so that you can reset to see if they are sporting their gift from you. This is not recommended if you want to avoid time traveling.
2. If you are familiar with the “diving for pwps” trick then you’ll have no problem with this one! Instead of filling your pockets with flowers, fill them with shirts you find acceptable for the villager to wear. Go for a swim and then run around waiting for a ping from that certain villager. It will definitely take a few tries unless you’re lucky but eventually they will ask to buy one of the shirts in your pocket!
3. Fill your able shop with designs you want your villager to wear. This is the least effective way, as the chance of a villager picking up one of your designs is all up to the game, but it stills works. You’re just going to have to hope the odds are in your favor;;
Hope this helps and that your villager cooperates!!