First time charge of new iPhone 13

You can just use the included Lightning to USB-C cord to charge your iPhone, or you can use the MagSafe charger for iPhone (sold separately). Your iPhone is designed to mitigate the effects of battery aging as you use your iPhone, so you shouldn't have to worry about your battery significantly degrading while you have your phone.

Charge the iPhone battery - Apple Support

Batteries do age with use and time, however, so you should make sure that you have Optimize Battery Charging turned on in Settings > Battery. This feature is designed to slow down the rate at which your iPhone charges while you're not using your phone, such as when you charge your phone while you're sleeping at home. This feature, even when turned on, doesn't activate right away as your iPhone learns more about your usage habits.

About Optimized Battery Charging on your iPhone - Apple Support

They're usually shipped in out in the middle of the charge range to mitigate issues with long-term storage of lithium-ion batteries that are fully charged. But if you're going to be using it on a regular basis, just make sure that it's charged, and definitely connect it to external power when it's being set up.