Fast chargers talk to the device its charging to see what it's capable of accepting and will only supply what the device is capable of.

No. There may be auto-ranging chargers, but not all are. The charger voltage needs to match two things, the source voltage and frequency (in the US 120 vac at 60 Hz) and the device voltage (3 volts, 9 volts, whatever). The wattage of the charger has to be at least the wattage required by the load.

>Can I use any volts/watts charger for my phone?

No.

In general:

1. When we are talking chargers, we mean a device which converts AC electricity from a wall outlet, to DC electricity required by an electronic device
2. The charger must support the voltage and frequency of your residential electricity supply. Any significant deviation from that can damage the charger and/or present a fire hazard.
   1. Some chargers support a range of input voltages for international use
3. The charger's output voltage (Volts) must match the device's input voltage. Any significant deviation from that (more than about 10%) could damage the device, the charger, or be a fire hazard
4. The charger's output current (Amps) and/or power rating (Watts, equal to Volts x Amps) should be equal or greater than the device's required current/power rating. A device will only draw as much power as it needs.
   1. A lower current/power rating can mean the device charges slower or not at all.
   2. A significant lower rating can damage the charger or device.
5. A standard like USB is smarter than most chargers, generally speaking any charger supporting a USB standard (like USB 3.2) must support the minimum requirement, and higher currents and voltages can be supplied by both charger and device negotiating for it, you don't have to worry about incompatible electrical ratings causing damage.
6. The plug on the charger must also match the power jack on the device. Don't assume a plug and jack are compatible even if they physically fit and the power ratings are compatible; the polarity must also be consistent (especially an issue on barrel plugs).

Or TL;DR:

1. Use a charger compatible with your country.
2. The Voltage on the charger must match the device.
3. The Amps and/or Watts on the charger should be the same or greater than the device.
4. A charging standard like USB or Lightning is designed to simplify things for consumers so you don't have to worry about electrical ratings or causing damage.

If your phone has a USB charge port- as most do- the voltage will be standard, at 5 volts. By default all USB chargers will provide this amount of voltage. If it's got the capability, when you connect it the phone may be able to use higher voltages, like 9 or 20 volts.

Your phone may want more power than a basic charger can deliver, in which case it'll charge slowly- and in some cases, such as a cheap or old charger, may overload the charger causing it to heat up or fail- usually by burning a component.

A higher-power charger may allow your phone to charge with higher current levels (more power), and charge more quickly. This would only apply to USB-C type chargers, the ones that are reversible. Older chargers are more limited in power delivery.

If your phone doesn't use a USB port for connecting a charge cable, you must use a charger with the correct voltage and current for it. I'm not familiar with any modern phone that does this, though.

The combination of charger and phone may not be able to communicate so no, you can’t just use any. For example Older iPhones will not be able to take an iPad charger. Check before you use. Having said that a lot of chargers and phones in recent years are more tolerant. There’s an optimal charging watts/voltage for each device. If you’re not sure, less watts is better so you don’t damage it. It’ll be slower but safer. A lot of smartphones are very similar now though, and are tolerant of the supply - usually 0.5A/2.5W/5V I believe