Gap between the screen and the bezels

You have 14 days from original date of purchase to return the phone (in the same country you purchased it, except in the EU, you can go to any Apple Store in an EU country). If the phone is determined to have a manufacturing defect, they will likely replace the phone for you. You need to take the phone and the original packaging and all accessories, like the charging cable with you. DO NOT wait past 14 days.

I'd take it back to the store you bought it from and show it to them.

No. First of all, all new iPhones purchased, come with a one year warranty against manufacturing defects. AppleCare+ plans, which are purchased as additional coverage, extends the care to two years and includes repairs at significantly reduced prices. I do recommend them highly as one never knows what can go wrong with a device which used in the hand out in the world all the time.

How long have you owned the phone and from whom did you purchase it?

You're welcome.