Depending on your specific goal, Netlify’s rewrites and proxies would be the most likely solution:
Quoting: “This means that the URL in the visitor’s address bar remains the same, while Netlify’s servers fetch the new location behind the scenes.”
The landing page might be a different site but it will look like a page at the same site to the person visiting. Note, you can rewrite from one site to another at Netlify only if all sites are on the same Netlify team (the limitations section of the documentation page above explains more).
If there are other questions about this, would you be willing to give a simple example?
For instance: A URL for site “A” should show the content for a different URL at site “B”.
If you share some example (or actual) URLs, we’ll be happy to share example redirect rules which preform the rewrite(s).
If there are questions, we’re happy to answer.