One of the great things about Android 8.0 used on the Motorola Moto G6 and other phones is that you can use SD card technology to increase the internal storage space for storing Apps, videos, music, etc. This allows you to save money by purchasing a phone model with less memory and adding storage later through cheaper SD card technology.
You'll need to go to the phone's Settings->Storage screen and select 'SD card'. Next select the three vertical buttons on the top right to open up the menu and select 'Storage settings'.
You can then select 'Format as internal' so that Apps can be stored in the SD card.
After formatting as internal storage, the SD card is seamlessly integrated with the existing internal storage.