You can try but be sure you have 6 hours or so to wait around.
Where? Some Apple Authorized Service Providers might allow for walk-in service. An Apple Store might do it if they have appointment slots that haven't been booked. I've gone into an Apple Store asking for help without an appointment and was told when they had available appointments, or that I could go when they opened the next day to be put on a waiting list for the rest of the day. I have also walked in with an iPhone issue (it was my wife) and we waited around for about 90 minutes and they took care of it without an appointment. There are no guarantees. We got lucky that they were willing to do it but they could have said to get an appointment.
The best way to do it is get an appointment. It's rather difficult these days with Apple Stores given then overwhelming response to the discounted battery service.
Question: can you do walk in for screen repair