iOS default font sizes - also available on https://www.iosfontsizes.com

ios-font-sizes.swift

let styles: [UIFont.TextStyle] = [
    // iOS 11
    .largeTitle,
    // iOS 9
    .title1, .title2, .title3, .callout,
    // iOS 7
    .headline, .subheadline, .body, .footnote, .caption1, .caption2,
]

for style in styles {
    let font = UIFont.preferredFont(forTextStyle: style)
    print("\(style): \(font.fontName) @ \(font.pointSize)")
}

results.markdown

Style	Font	Size
.largeTitle	SFUIDisplay	34.0
.title1	SFUIDisplay (-Light on iOS <=10)	28.0
.title2	SFUIDisplay	22.0
.title3	SFUIDisplay	20.0
.headline	SFUIText-Semibold	17.0
.callout	SFUIText	16.0
.subheadline	SFUIText	15.0
.body	SFUIText	17.0
.footnote	SFUIText	13.0
.caption1	SFUIText	12.0
.caption2	SFUIText	11.0

Thanks 👍
This is useful documentation :)

Thank you!
I am guessing these results are from running the code with the default user font preferences?

@NikolaKirev Correct, this is just at the default dynamic type size. You can see a graph of what happens to the type sizes in this graph.

what are the font sizes for iPad?

I think when considering accessibilities this won't be the correct size anymore.