Is there a hotkey to subdivide geometry? I’ve been following this tutorial for a model, and I’m wondering if there’s any hotkey to change an extruded plane (like it was done in the video) from this: 



To this: 



If not, do I need to use a cube mesh and edit it?
You're looking for subdivide. It doesn't have a shortcut by default, but you can assign a custom hotkey by rightclicking on the menu item under mesh-> edges -> subdivide 


in my case it's set to alt + w