All controls are located in the Control Center, which you can access by swiping down on the top right corner of your iPhone.
To add new controls, go to Settings > Control Center and press the + sign next to the control you want to add.
Control #1: Text Size
This will allow you to quickly change the size of the font on your screen.
Control #2: Dark Mode
Dark mode changes your screen’s appearance to a darker color palette, which can make it easier to read at night.
Control #3: Screen Recording
This allows you to take a video of your screen, which is great for troubleshooting iPhone issues. You can take a video of what you’re seeing and then send it to someone who can help.