Not a chance, if your fleas have gotten to the point you internet searched how to get rid of them then it is too far advanced. That being said, there is alot of people that think catnip does work, because they saw it on the internet. Parrot sites regurgitate whatever their handlers tell them too with no first hand context.
I can tell you from first hand I tried rubbing handfuls of crushed catnip plants it did nothing to affect fleas. They group up on the head and cheeks and I rub it fresh off the plant to his face but the fleas hardly notice. Maybe I am using the wrong bush but the cat really likes it. Catnip was mildly effective against mosquitoes, i mean not really but it was better than nothing, for both me and the cat.
Essential oils might work better but like with Lavender, it can make them sick, and believe me they will want to lick themselves. Everything you read on the internet has its opposite counterpart you can read on the internet, thats why first-hand experience is so important. here is an article that contradicts everything else by saying lavender oil is good for cats. Use good discernment skills