The potential issues with fast charging are mitigated through technology, but it isn't entirely gone. There's a small but noticeable difference. Fast charging is still a calculated tradeoff between speed and battery health, there's no such thing as a free lunch so to speak.

Ideally if you can accommodate a slow charger in your life, by all means please do. However, it should be noted that the most damaging state a battery can be in is 100% fully charged for an extended period of time. Hence why some Electric Vehicles and consumer device have charge limits, which iPhone lacks user-control of.

With that said we can have a few strategy in preserving battery health. I dual wield an XR with a LG V35 with Quick Charge 3.0. I don't ever charge them overnight unless roster puts me on an early flight. During my morning routine, I plug them in right after waking up, and by the time I leave the house both phones will be at 100% or close to it.