Connect your smartphone with a USB cable to your Pc.
Download the tool scrcpy link:
scrcpy
Look under assets for the version to download.
The screen of your smartphone is duplicated on your monitor and you can use the mouse and keyboard from your PC to operate your app on your device.
The tool requires ADB to be installed on your PC and USB debugging activated on your device.
I use this tool to make screenshots from my running app on the device.
The tool can also connect wireless.