I'd recommend a quick charge.
Damage do not think much, now the charging technology is much smarter than people, mobile phones and chargers have charging protection.
Fast charge, basically, the charging speed is fast in the front, and the back will also reach the trickle charging stage, preventing the temperature from being too high and protecting the battery life.
Now after the release of iPhone 12, the original 20w charger officially logged on Apple's official website, and the price has dropped a lot of the original 18w.