How HTC 10 charger works on other devices?

I had a charger from my previous phone and their specifications were 5V/1.2A, I used it for everything except the HTC 10 but recently the charger died so the only one left is the HTC 10 charger, their specifications are 5V/2.5A, 9V/1.7A and 12V/1.25A, making a research I found that an excess of voltage burn electronic devices and this charger allow different voltages so my question is, what is going to happen if I connect my Bluetooth controller (GameSir G4s) or my headphones (Sennheiser Momentum 2.0 Wireless)? Both only accept 5V, more than that will burn it

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