It’s 60px minimum height or width, I’ve just updated the post to say “at a minimum” because you’re right that it depends on the content and of course a larger button would be fine to use.

It’s more likely the height would be closer to be 60px than the width as you wouldn’t fit many words in, unless the font size was tiny.

Also if you want more information about this then Apple have posted some guidelines on using their Apple Pay button and say at a minimum on a retina screen the height should be 60px.

https://developer.apple.com/design/human-interface-guidelines/apple-pay/overview/buttons-and-marks/