I mean other than being called “Sir” or “Dame”.
Is hearing the “Sir” or “Dame” before a persons name enough to turn the average English person into an eager to please monkey butler? Anything tangible in this honorific? Better service in pubs? Pogues tix easier to get? Sir Anthony Hopkins rings you up to see if you want to partake of a steak and kidney pie at the club with him? Do you get to wear the crown jewels for 10 minutes on Christmas Day? Anything?
Speaking as an “average English person” no, there isn’t generally any real advantage gained.
Although generally honourary knighthoods are awarded to people who have achieved something - so if you come across someone with one then chances are that they are owed some respect for whatever they have done.
First of all we need to clarify some terminology here. An honorary knighthood is one that is awarded to a person who is not a British or Commonwealth citizen (such as Bob Geldof, Rudy Giuliani, Stephen Spielberg, Alan Greenspan etc. etc.). They are not officially allowed to call themselves Sir or use it on any letterheads etc. They are allowed to put KBE, or whatever designation they’ve been given, after their name. There have been threads before about whether US citizens should accept such awards if you want to search for them.
As far as regular knighthoods are concerned, there are numerous accounts of them getting people better seats in restaurants and dinner invitations from social climbers, but the average person wouldn’t be particularly impressed and some people would lose credibility following a knighthood, especially if they’ve spent their lives complaining about the honours system being anachronistic or elitist.