When modifying the contact offset in a project it appears to have no effect. The setting that worked in a previous engine version (4.19) now collide in the same way as the default settings.
Result: The two cubes will collide even though the contact offset has been changed
Expected: The Contact offset would affect the collision of the two cubes so that they no longer collide
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-68523 in the post.