Updating the application software and vice-versa for iPhone 6

Hello!
Good day to all of you! Can you provide me additional information about iPhone6? I want to know how to properly use it. I want see on how to set this phone with automatic updates? Is there any way that I can disable it also? Can I change the size of the icons and texts in the screen? How can I revert it? Can you provide me step-by-step instructions for this? Can you provide me also alternative ways on how to do this in my phone? Your reply will be much appreciated.
Thank you!
