mac man help page up + page down

If I understood you correctly, you want to skim through manual pages more efficiently.

By default, man uses less as its pager. In less, you can use:

• Space or f or Control⌃-f to advance one page
• d or Control⌃-d to advance half a page
• b or Control⌃-b to go back one page
• u or Control⌃-u to go back half a page