The lying scumbags often use the “medically proven” line, without getting in trouble, because their product contains Yohimbe, which has been shown to have a positive effect on penile blood flow.
So some people may in fact feel an improvement in erections from the effects of Yohimbe, and a stronger erection can mean a bigger erection, so they can carefully word the ad to imply that the pills make your dick bigger.
You can buy the basic ingredients of what is in the phony enlargement pills for a fraction of what the pills cost. Yohimbe and arginine, for example, may help your erections, but no pill is going to grow your dick. Don’t fall for the scam.