You can add a “Supported Agent” in “Project Settings/Engine/Navigation System” of the size of your pawn (Fill Nav Agent Radius and Nav Agent Height).
Are you using a CharacterMovementComponent in your pawn/character? If yes, you then can set the same values in the component under Nav Movement or have “Update Nav Agent with Owners Collision” checked (it is checked by default).
Your character should now choose a more appropiate path further away from the obstacle!
I am not an expert in this, though, this is just how it worked for me when I needed it!