Hello lourdes104,
Thanks for asking the Apple Support Communities for help with purchasing your iPhone online, and picking it up at the Apple Store.
Depending where you are, this should be an option once you go through and choose your device storage capacity, color, and other options online, then pay for the device. You should then see the options for delivery or pickup in a store of your choosing.
Check this link: Buy iPhone X🅁
For pickup in Orlando, FL, there are two stores, Apple Millenia or Apple Florida Mall. You can also check Apple Altamonte which is nearby in Altamonte Springs, FL.
If you are in an area that can't purchase online, you always have the option to walk-in to the store and work with someone to help you get the best iPhone for your needs. If you will be trading in a device or transferring your data from your previous iPhone, please make a backup, and review this help article: Get your iPhone, iPad, or iPod touch ready for service - Apple Support
This article will help you make backups for an iPhone: How to back up your iPhone, iPad, and iPod touch - Apple Support
Thanks and have a wonderful day.