Hello there,
In a two-way trust (Transitive), both domains that are involved in a trust relationship trust each other.This means that authentication requests can be passed between the two domains in both directions.Some two-way relationships can be non-transitive or transitive depending on the type of trust being created.
Forest trusts help you to manage a segmented AD DS infrastructures and support access to resources and other objects across multiple forests. Forest trusts are useful for service providers, companies undergoing mergers or acquisitions, collaborative business extranets, and companies seeking a solution for administrative autonomy.
https://learn.microsoft.com/en-us/azure/active-directory-domain-services/concepts-forest-trust
Hope this resolves your Query !!
--If the reply is helpful, please Upvote and Accept it as an answer--