Before launching emulators you should check if there any emulator created. You can use the below command.
C:\Users\Nadeem Akhter\Desktop\vscode>flutter emulators
2 available emulators:
Android_TV_1080p_API_28 • Android TV (1080p) API 28 • Google • android
Nexus_5X_API_28 • Nexus 5X API 28 • Google • android
Now you can launch your emulator. Flutter has one command flutter emulator that helps you to launch the emulator.
$ flutter emulators --launch Nexus_5X_API_28