I have a modless Sims 4 with all EP, GP, and SP (Besides My First Pet), and they'll change into whatever. They do really like their 'default' Everyday though, as said above. I have a Sim who is a Stylist, and regardless of weather, he'll change into that outfit to leave for work, even if he's wearing a Hot Weather or Cold Weather outfit. Besides that though, all four in my household (and even other neighbors I've given multiple outfits) will wear different things from time to time. Worst comes to worst, you can do it manually.