No, supplementary angles are not always congruent. Supplementary angles are defined as two angles whose measures add up to 180 degrees. This means that one angle can be larger or smaller than the other, as long as the total is 180 degrees.
For example, an angle of 130 degrees and an angle of 50 degrees are supplementary because 130 + 50 = 180. However, these angles are not congruent since they do not have the same measure. On the other hand, two angles that each measure 90 degrees are also supplementary, and they are congruent because they are equal in measure.
In summary, while supplementary angles always sum to 180 degrees, they do not have to be congruent unless they are specifically equal in measure.