electrical length - degree
Strictly speaking, they are not related at all.
Characteristic impedance, on something like a 2 conductor cable, is simply a measure of the voltage divided by current at a physcial point. More specifically, it is the amplitude of the voltage wave travelling in one direction on the cable divided by the amplitude of the current wave travelling in that same direction.
Electrical length implies time delay or phase shift.
impedance and electrical length are independent.
You can have a 50 ohm cable that is 1 degree long, or 100000000 degrees long. In either case it is exactly the same cable, only with 2 different lengths.
You can have a 20 degree long cable that is 10 ohms, and another 20 degree long cable that is 200 ohms. IF the two cables are made of the same material (same dielectric material mostly), both would have the same physical length, but quite different cross sectional geometries.
Note, a cable with an electrical length of "20 degree long" has a thru phase shift of 20 degrees at the ONE frequency that you make the measurement at. At a different frequency, the electrical length will be a different phase.