Easiest way to accomplish what you want: host a static html page on blog.example.com that redirects the user to example.com/blog:
https://stackoverflow.com/questions/5411538/how-to-redirect-one-html-page-to-another-on-load
I’ll note that a server side redirect would be preferred if this is for professional or business use. For personal shit, go nuts
Oops, prepare for the secret service visit!