Q: when i buy a new iphone will my pictures that are on my old ones be lost when I reset it?

Hi

Go to iCloud on your old iphone and back up.

When you set up your new iPhone just use the same Apple ID / password

Then you will get all your Apps /Data on new iphone.

Before you sell old iPhone turn off find my iPhone .

Then restore to Factory Settings .

Then its ready for new owner to use.

Cheers

Brian uk

If you are using a computer to sync your phone, just back up your old one and when you restore your new one from the old ones back up the pictures will be there.

Apple support document showing all the options

Transfer content from an iPhone, iPad, or iPod touch to a new device - Apple Support