There will always be situations when you need to charge your phone, but you don’t have the charger with you. Apple doesn’t include a charging block with the new iPhone 12, though it does include a Lightning cable.
You can plug in any Apple certified iphone 12 wall charger to charge your phone, especially since most handsets support wireless charging and USB C standards.
The most common specification you will see on a charger is the Watts (W). This is simply how much energy it can push towards your phone at once. Laptops and tablets will have chargers that have a higher W value. This is because they have larger batteries to charge. Don't be surprised if the charger doesn't work with your tablet.
The wattage of the charger and the maximum wattage your phone can handle will determine how quickly your phone's battery life goes from zero to 100. (This information should be easy to find with a quick internet search). For example, the new iPhone 12 can take up to 20 W.
The official Apple 20-W charger will charge your iPhone 12 times faster than the Apple 5-W charger. The 20-W model is compatible with larger iPad tablets. The 5-W model does not.
This is also true for laptop ports. The latest MacBook Pros can produce 10 watts from their Thunderbolt/USB C ports. They can beat 5-W chargers, but they can't match the 20-W models. This assumes your phone can consume up to 20 W. If your phone's battery is at least 10 W, then the MacBook Pro with the 20-W charger will recharge it at the same time.