Looks like knock knees, not usual with men who are typically straight to bow leg.
The cloth twists in the leg causing the wrinkling at the knees as they are coming together and opening out for the feet.
In bespoke this would have been allowed for in the cut of the trouser, the leg needs to be cut closed. However thats no help here.
It can be alter though the process is a little unorthodox.
Rip out the inside leg seam and side seam to crotch level, stretch the cloth on the side seam above and below the knee and shrink the cloth on the opposite side (inside leg seam) the shrinken cloth can be held in place by using straight grain tape.
Would only advise this as a method of last resort, and may not work with light weight cloths and non wools.