1 create new folder named MSFS 2020 on for e.g. D drive
2 copy root_game_folder Packages from
C:\Users\YourUsername\AppData\Roaming\Microsoft Flight Simulator
to D:\MSFS 2020
3 after that go to
C:\Users\YourUsername\AppData\Roaming\Microsoft Flight Simulator
4 open with notepad file named userconfig.opt
scroll down to the bottom and edit last line
e.g.
InstalledPackagesPath "C:\Users\YourUsername\AppData\Roaming\Microsoft Flight Simulator\Packages"
Packages is root game folder
change
InstalledPackagesPath "C:\Users\YourUsername\AppData\Roaming\Microsoft Flight Simulator\Packages"
to for e.g.
InstalledPackagesPath "D:\MSFS 2020\Packages"
save changes