I have hornee jeans and they came with knee armour they pull on over the knees and are held in place with hook & loop straps. Don`t know if they sell them separate from the jeans. found these same as hornee protectors https://www.modulemoto.co.uk/armour.html Geoff
I've been using some of these with kevlar jeans for a good number of years https://www.sportsbikeshop.co.uk/motorcycle_parts/content_prod/63389 Comfortable enough for a full days riding and never move ... hopefully I'll never have to test there crash protection
I actually have a pair of these, different make, but same thing. They're almost OK with my jeans but not for more than an hour or so. If I can get a bit more room in the leg they'll be great.