@Gladiator There are a few mods in the workshop that do it by adding buttons or hotkeys, but you can also do it by adding a launch parameter to CK3 in Steam. The debug setting people are referring to is called instant construction or fast construction, and when it's toggled it makes all player buildings (modded or vanilla) construct instantly.

Debug disables achievements though, this won't

I didn't know it was. How do you activate the debug settings ?

So just activating the Debug setting then

isn't this already a feature in debug?