I'm working with a client who is expanding from one location into a (nominally) national brand. Two new locations are opening across the U.S. from the parent location, with several others scheduled to come online during the second half of this year. After that -- who knows, but I've heard projections of 30-40 locations by the end of 2022.
The owners want each location to have its own cloned website with just the location and contact information customized. (Kind of like those multilevel marketing sites except named after cities instead of anonymous ID's.) Local owners would probably also have some ability to add content, such as a blog, weekly specials, etc. The cloned sites would be on their own subdomain (or perhaps a subdirectory) of the main site.
I've been out of the SEO world for a while, but I'm concerned that plan won't work well for local SEO and could potentially harm everyone for duplicate content.
What's considered best practice these days for deploying local sites for a national brand? I'm interested in overarching concepts (particularly relating to local SEO), as well as specific technologies for deployment and management.