There's all manner of purported methods of treating herpes with peroxide. Many with no real science behind them. Which specific ones are you talking about.
Peroxide of any kind works kind of like bleach by being highly reactive due to its instability and reactive oxygen species and that reactivity allows it to wreck biological systems. Like bleach it will kill surface virus and act as a general disinfectant. However, in that respect its really no different to any disinfectant used to clean skin and surfaces.
Beyond that there's a lot of dodgy stuff out there.
When playing rugby, its not the winning that counts, but the taking apart