Restrict items based on author, not users

Is it possible to restrict items based on author of the post, not users? For example, a user/author post something on my website and not all content will be displayed to the public if the author/user is level 1 or below.

something like this:
if level of author of the post > level 1
then display this
end if

And i’m wondering how to write the first sentence in php: if level of author of the post > level 1