Establishing one-way trust from Company B to Company A would allow users from Company B to access Company A's resources using their existing credentials. Implementing attribute-based access control would allow users to have different sets of rights and privileges based on their attributes, such as department and IP address. Verified Reference:
https://www.cloudflare.com/learning/access-management/what-is-sso/
https://frontegg.com/blog/a-complete-guide-to-implementing-single-sign-on
https://learn.microsoft.com/en-us/host-integration-server/esso/enterprise-single-sign-on-basics