4-5cm is a big change. I don't think you can change that much in one go and have it work.
Having my saddle too low ends up hurting my right knee somehow. Screwed up my saddle height at PBP in 2019, and ended up with a knee the size of a grapefruit. They have massage therapists every 100km, but I needed one every 80km
I had my best sleep of the ride waiting for a médecin, too bad it put me so far behind on the clock.