Is there a way to have Write.as point to a path

Hi

Beginner developer here.

I have a app created using React at example.com and want to have my write.as blog on example.com/blog

I see that there is a option to have custom domains. Is it possible to use express and proxy to the custom domain.

I am a little out of depth so wanted to see if it’s possible at all. The main reason for doing this is for SEO purposes.

I would greatly appreciate any help.