Can I return my iPhone?

Yesterday I bought my first apple product, iphone 13. I bought it at the store, not over the order and I paid in cash. I'm wondering if I can return that device since I only bought it yesterday and will my money be refunded because I opened it? Or can I return this device and take pro max at an additional cost because the screen size doesn’t suit me? Thank you!

[Re-Titled by Moderator]