This is referred to as a 2 Piece Style A Ledge Jumper to shift the downpipe as it comes down the wall

The offset is about 5" for this 4"x5" downspout

The average length is about 20" - This unit is 2 separate pieces so you do have a bit of wiggle room for length

This Style A has the wide part against the wall and the leg will come at you off the wall.

White factory finished aluminum downspout section