sometimes when you're reading vim's built in help you want it to take up the entire page
using tabs
run :tab help [help query], this will open the help for that search in a new tab, there is fine for a one off search, but if you're planning on doing multiple help queries you'd end up with many tabs, which might not be what you want
making help the only screen
with this approach, start by opening help regularly, it should open it in a split, then run ctrl-w o to make it the only visible window. Now you can use the :help command many times over, while maintaining fullscreen. TODO how to exit that window safely