I believe this relates to multisite but if it doesn’t, sorry in advance.
I have a client with an existing website who wants to create a new website with a new domain (not a subdomain or subfolder domain). He wants the new website to have some static pages that are specific to the new website and some pages that will be exactly the same as the existing website and will update when these pages on the existing website are updated. The themes for both websites can/will be the same.
I believe multisite and domain mapping can achieve this but I’m not positive and I’m not exactly sure of the steps to take.