When I click an engine shortcut:
It also opens the launcher even though I never clicked the launcher.
I find it annoying that it does that because the launcher takes up a lot of Internet speed and I often am disturbed with other things that I am doing due to the launchers usage of my Internet.
My suggestion is is that the launcher doesn’t open when you only launch the engine.
Everyone is annoyed by this but it is unfortunately as designed and will likely not be changed.
You can however rename the launcher.exe to prevent it from opening.
Designed to be annoying 
Jam a file named “PerforceBuild.txt” into the Engine/Build directory.
When the editor opens without the launcher, it won’t open the launcher.
https://answers.unrealengine.com/questions/17919/prevent-the-editor-from-launching-the-launcher.html
Cheers