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

It's possible to draw in Google Docs directly to add an artistic touch to your documents. Here's what you need to know to do ...

Since there isn’t an actual border feature in Google Docs, you can add objects to your document and give it the appearance of having a border. Let’s look at the three ways in which you can do that.