Best practices
Prefer keeping a box relatively small in comparison with its containing view.
Consider using padding and alignment to communicate additional grouping within a box.
Content
Provide a succinct introductory title if it helps clarify the box’s contents.
If you need a title, write a brief phrase that describes the contents.
For the complete guidance, including worked examples and illustrations, see the canonical page: https://developer.apple.com/design/human-interface-guidelines/boxes