No but you shouldn't need an instructor. Try riding with a headcollar and see how you get on. Then if it goes well you could start trying bitless bridles. I find it the same as riding with a bridle.
The one difference I've found is that I need to give more half halts with my seat as my horse starts to lean on the bridle after about 10 minutes of bitless riding.
Have a look on YouTube. There are loads of videos on the different types of bitless bridles and how to introduce them. Also look up 'one rein stop'. And start in a familiar enclosed space.
Firstly you really need to research the different kinds of bitless bridles and the way in which they work, i.e. a Hackamore will work a completely different way to say a Bosal and you need to know the difference, as well as having some kind of understanding of the various nerves which traverse the horse's face & head area as this is fundamental, before you start out.
And yes I know it sounds obvious but do make sure that the first time you try anything out you are in a safe place such an enclosed school - just in case anything goes wrong.
Just a suggestion, and do with it what you will, but a good bitless set-up to perhaps try initially would be the "Orbitless". There is plenty of support & advice re. fitting etc available on their FB page.
I found the Orbitless was the only thing my old gal (trigeminal nerve headshaker) could tolerate on her; also my current coblet goes really well in it and is very responsive.
Thank you folks. I have tried a Dr Cook X under. Didn’t like it as it didn’t release quickly enough. I have a Transcend side pull single rein which is ok but pony tanks off in Canter. My back isn’t good - have broken it twice - so I’m stiff & my seat isn’t as strong as is needed. I do a lot of in hand / ground work & pony does respond to voice but can be strong at times.