there is a surgical procedure im aware of that increases the flaccid length of the penis by cutting ligaments near the base of the penis, but i;ve seen the side effects and to be honest i;d rather shrivel when its cold
the surgery also does nothing for the errect length
no idea if any if the other techniques work. but given penis length only really matters if yu;re sleeping with someone and if theyare scrutinising the size of your todger, you have to pretty much be in there anyway