Well you can move files (photos, music, videos, etc.), not apps, to the SD card and that will give you move space. You can also delete/uninstall apps that you don't really use.
If you want to move apps to the card there are changes you will need to make, see below.
First, you need to be using a phone that is running at least Android "Marshmallow" (or newer) or be able to upgrade to it. Second, you will need the instructions I am including below. And third, you need a phone that has not been restricted by the manufacturer from making this change. Which does happen.
NOTE: If any of the steps are missing on your phone, or they don't work for you, then you have a phone that either has an older Android version or has been...