Second this. We want a local/global account with a single linked idp. This is to normalize all users. In this case we want to force the use of the linked idp for a given email domain. I.e alice@corp.com MUST login with Corp.com SSO. Bob@whatever.com can login in all ways Local or linked.
Another way to look at it is if I see a Corp.com email it’s just a lookup to use the Corp.com company sso.