You can enable USB debugging mode. by two ways first by mobile settings and second by using combination file. use combination file in case your device is locked or google account locked or FRP locked enable.
USB Debugging Mode – Samsung Galaxy
If you need to facilitate a connection between your device and a computer with the Android SDK (software development kit), view this info.
From a Home screen, tap Apps > Settings > About phone. These instructions apply to Standard mode only.
Tap the Build number field 7 times. This unlocks Developer options.
Tap ABOUT PHONE (located in the upper-left) to go back to the previous screen.
Tap Developer options.
Ensure the Developer options switch is in the ON position.