To acquire extra costumes, head to Rory's Cave and locate the "Get Costumes" button. Once there, you can purchase costumes using the coins earned by progressing through levels and receiving daily log-in rewards.
By actively playing and logging in regularly, you accumulate coins, providing you with the means to access and expand Rory's wardrobe.
Simply hit the "Get Costumes" button, and with your hard-earned coins, unlock new and exciting outfits for Rory to wear during your adventures.