Although there isn't a direct feature to create borders on Google Docs, there are 3 workarounds that you can use to create that appearance.

In this table-themed HTML tutorial, I’ll explain how to make a basic table, add and remove borders, create layouts, make cells the shape and size you want, place cell contents, and add color.

You can add a border in a Google Docs page using a workaround, since there's no built-in border tool for doing this automatically.