How big is a "big O."? I have had Plantar warts on my feet of all sizes on and off since I was 13. I've had them removed with acid and with burning/freezing. Sometimes they would stay gone and sometimes (no matter how painful the treatment, and it was always painful) they grew right back. You might get rid of this O., but it's likely he will get more, as some of us are prone to these and some people aren't. (No O. else in my family has ever had O. despite sharing showers and bathroom floors for decades.)
What I eventually found out, through experience, is that sometimes they go away completely on their own. I've had that happen.
I now have O. on the ball of my foot. It's been there for several years. I will NOT ever go to a Dr. again about a Plantar wart, because of my previous painful experiences. If mine bothers me, I use over-the-counter salicylic acid on it once or twice, then remove the dead skin and it's better.
If your son's wart doesn't cause him pain and is not spreading (creating more new warts) you can choose to leave it alone. If it is causing pain, the cause of the pain is the dead skin on top of the wart, not the wart itself. It feels like you have a small stone in your shoe. You can scrape this dead skin off after a bath quite easily (and also the OTC treatments will loosen this dead skin).
I would not put my child under anesthesia for a Plantar wart. I would use duct tape again, or other OTC treatments.