You can configure Android to keep the screen of your device awake while it is charging. This option can be enabled/disabled under the Developer Options menu.
Keep the Screen of Your Android Device Awake While Charging
The first step is to enable the Developer Mode. Go to Apps > Settings> About Phone and then continuously tap on the Build number until a message that reads, "You are now a developer" is displayed on your screen.
Head back to the Settings menu > General > Developer options. Tick the Stay awake - Screen will never sleep while charging checkbox: