The Verge has a handy guide to all the gear you'll need to fast charge the iPhone X, 8 or 8 Plus. Here's a quick rundown of the key details.
The Fastest Fast Charging Option
According to Apple, you'll need a USB-C to Lightning cable to fast charge your new iPhone, but the company ships each phone with a regular USB-A cable instead. That means you'll need to buy a new cable, and in this case you should really get it from Apple. ($35 for a 1-meter cable or $49 for 2 meters.)
The company still has total control over Lightning input, so any third-party USB-C to Lightning cables you might see are non-sanctioned and might not be safe to use. That's particularly important when you're transferring as much power as possible to your new iPhone.
Thankfully, you won't need to spend as much on a USB-C charging brick, since that technology isn't controlled by Apple. If you have a new MacBook, you can use that brick for your iPhone. If not, The Verge has a few suggestions, with the cheapest being Aukey's for $US23.99 ($31).
Cheaper Fast Charging Options
If you want a faster charge but don't feel like shelling out for extra cables, you still have a few options. Just don't expect to hit 50 per cent battery power in 30 minutes if you go this route.
The easiest solution is to just use an iPad charger, assuming you have one lying around. Apple added this option years ago with the iPhone 6, and it's still a great way to give your charging speed a boost.
If you don't have the right charger on hand, you can also grab one for pretty cheap. Amazon has a charging brick with two USB ports for just $US9.99 ($13) that will get the job done just fine.