Make a plugin enabled by default for all projects

Each Unreal plugin has a description file with the suffix .uplugin. If you want to set a plugin to take effect for all projects, you can modify this file to achieve the goal.
For marketplace plugins, this file can be found under

C:\Program Files\Epic Games\UE_[Version num.]\Engine\Plugins\Marketplace\[Plugin name]

For example, the description file of GraphFormatter is GraphFormatter.uplugin in the project root directory.
This is a json file that can be opened with any text editor.
Add this code

"EnabledByDefault" : true,

to the first level of brackets above

"Installed" : true,

and change "Installed": true to false.
In this way, the engine will regard this plug-in as a built-in plug-in.