Druid keeping a Colossus Elixir

 Oversized Owlbear Fun

The size can be an issue when moving through doorways and such, but the owlbear could jump the height of almost any climbable surface... His size, although an inconvenience at times, can create a wall of meat between enemies and your characters - he can become the chokepoint.  This video is purely to give a view of the size, and example of mobility (jumping)... at a very random point in time in the game.

(smaller)

I used the Wizard to cast the size changing spell to stack with the colossus elixir; the size description and weight barely change - but, the standard increase in tile* usage... e.g. it IS bigger.  Actually, I read it too quickly - it appears there is a bug with the weight, although I'm not sure if it is purely visual or not (as weight effects damage when you land on things).

(bigger)

Astarion comes up to the (larger) Owlbear knee.

(smaller large size in video)