Yes, you maintain functional control over your phone's operations inside the Outex phone case.
Keep in mind that water pressure will limit touchscreen responsiveness underwater. This is normal and affects all underwater housings. Water pressure confused the phone's touchscreen, just as if you were trying to control it using more than 2 fingers at a time. Use the side/hard buttons to control imaging features. Most phones are pre-configured to operate that way in camera/video mode, for both functional and ergonomic usability. You can even customize/reprogram those buttons in settings to better fit your needs. Change settings above water using the touchscreen, then the hard/side buttons below the water.
Most phones also enable to you to access the Camera/Video functionality directly from the lockout screen. That's your best access for underwater use, since accessing it directly also prevents other functions and apps from accidentally interfering with your imaging functions. In other words, launching the camera function from the Lock Screen keeps all other functions of the phone out of your video/camera operation while in use.
For additional insights, tips, and tricks for phone operation use our Phone Photography Guide in our user community page here.