In order to do this, the software must run on the same physical server.
So for example, you could have Wordpress installed within domain.tld/news (or just /) and IPB installed in domain.tld/forums. Those would all be installed within the same server in the same virtual host , etc.
If the news or blog site are on different physical servers, you would need to use subdomains.
This is not an IPB limitation... it's a limitation of DNS itself. DNS says domain.tld goes to a specific server (such as www.domain.tld). Once it's at the server, it handles all paths below it (such as /news/ or /blogs/).
Technically there are ways to work around this if you're using a CDN as a proxy... as it could be POSSIBLY configured to go to a different origin based on path matches, but that is WAAAAAY outside of the scope of this discussion. 🙂