Just a warning that all the clinical evidence provided in that review was done by (or funded by) companies using their own products. It's a major issue in a lot of dermatological research as noted by this article from Harvard (https://www.hsph.harvard.edu/nutritionsource/collagen/).

It's worth noting that the American Academy of Dermatology has no recommendations regarding dietary collagen but does have evidenced backed advice for those looking to maintain healthy skin:

https://www.aad.org/public/cosmetic/younger-looking/firm-sagging-skin

https://www.aad.org/public/everyday-care/skin-care-secrets/anti-aging/reduce-premature-aging-skin