Right click on a skill bar to set a level.Right click on an aspiration goal to fulfill it.Right click on a moodlet to remove the moodlet.

The first one lets you take full control of gameplay via easy shortcuts in the User Interface while the second lets you control pretty much every aspect of the game. Probably one of the two biggest mods used by the modding community are UI Cheats Extension and MC Command Center. Plenty of us in the community who play The Sims 4 on PC like the additional layer of control in Gameplay that certain Mods provide.