Adding site from dev to production

I have a wordpress multisite install running on production with 3 unique sites.

I need to build a new site to add into this multisite install, but I need to do it in a dev environment and then push it to production when it’s finished and approved. I would like to know the best way to do this without messing up the other sites.

Should I do a single WP install on dev and then merge it into the multisite or try to replicate the multisite in dev and add the new one and then try to push it all live and just change the url in the db (if it’s as easy as a single install).

Sorry if this has been asked before, just send me a link to the post if it has.

Thanks.