Fast charging in Iphone 11

You can fast charge an iPhone 11 and you can use a 3rd party power adapter. See the following from: Fast charge your iPhone and iPad - Apple Support

• A comparable third-party USB-C power adapter that supports USB Power Delivery (USB-PD)

i agree with foxfifth in full, BUT pertaining to the part where you asked about battery health, heat is a phone's enemy, lets say you never use any other charger other than something like a 30 watt charger and above, it'll one, heat up your phone a lot every time you charge it with the charger, and two, it'll get to 100% faster than a normal charger which is ok during the day for a quick charge, BUT at night its really bad for your phone because lets say you get 8 hours of sleep but your phone gets to 100% within 2 of those 8 hours, it'll just sit there charging for hours till you unplug it, now while yes, apple has a chip in the phone to minimize the impact on the phone in situations like this, it still isn't perfect and i'd be careful, so basically what can you take from this? use a 18 watt charger (or more so just in general the charger that came with the phone) for normal charging, and use a charger over 18 watts ONLY when you need to, and try and avoid using too powerful of a charger because it'll heat your phone up and as i said, heat is your phone's enemy, try and only purposely let it heat up with things you actually need to do, like playing a game, if it heats up while playing a game, unless its really hot, its ok to let it do its thing while playing, BUT for something like charging, if its unneeded, try your best to avoid using an overpowered charger when you dont need to, i hope this makes sense and if you need clarification, have any other questions, comments, or anything, feel free to ask/say and i or someone else would love to help more (and again, this is an ADDITION to what foxfifth said, do not think of either mine or his post as more superior, both our posts are just as important)

Not really relevant or true. The phone controls its own charging, including monitoring the internal temperature of the battery. The current capacity of the power source is totally irrelevant. If fast charging raises the temperature too much the internal charger chip will slow it down. See—>If your iPhone or iPod touch won't charge – Apple Support, specifically the section “If your device stopped charging at 80%"

The phone will not be damaged by any charger provided it complies with USB standards that Foxfifth described. You can use a compliant usb-c 100Watt charger quite safely. The phone will control the current.

Battery ageing is dependant on number of full charge cycles and it should age down to 80% after 500 cycles.

ok ok thats true, honestly i wasn't thinking of that too much and overall just plain out oblivious to the fact that temperature plays such a role as well, honestly imma just delete my post because both of you (with the points made) counter everything i said, i was trying to find my source because i remember support telling me what i put down, that you shouldn't use fast chargers all the time because it'll heat the phone up and degrade the battery faster and they linked me to an apple support article but honestly i cant find it at all anymore and you do make good points (along with what peter said), and also ngl considering both yalls levels are a lot higher than mine it'd be foolish to argue (foolish on my part), especially considering i have no clue where the support article they linked me to is

ok well edit, apparently deleting your own replies doesn't exist, for some reason i cant even edit it, welps-

Well, actually, before the advent of Lithium chemistry batteries and smart chargers you would be perfectly correct. But Lithium is so picky about charge management that the “old” technology, where the power source regulated the charge rate, just doesn’t work with it. This is critical, because Lithium itself, even though it is a metal, it highly flammable and burns with a very intense and dangerous white heat. In fact, lithium fuzes are used to ignite thermite bombs. And there is a huge amount of energy in a Lithium battery in a very small space. So it is absolutely essential that the charging is closely monitored. (Even then stuff happens; think about the Samsungs that caught fire and were banned from airplanes a few years ago.)

The solution was the invention of smart chargers that are actually computers themselves. All Lithium-powered devices use a charger chip, in the iPhone it is the U2-Tristar IC. This moves the responsibility of regulating the charging from the power source (where it still is for 12v car batteries and older NiCd and NiMH batteries) to the device itself.

It’s good to see you here in ASC as a volunteer. Stick around!