@JadeHughes Welcome to the forum!
First, could you explain what you mean by “force explicit send”? (my guess would be a policy that the sender can’t obfuscate their email address?)
Second, I think you have two valid requests here (forcing explicit send and the ability to restrict domains you can send to). But we have a voting system (for feature requests) on the forum, that makes it necessary that feature requests are about one specific thing only. (otherwise, it’s not possible to interpret votes – and how should someone vote who would very much like feature A, but under no circumstances feature B?)
So, I’m going to close this request (with some delay for further clarification) and would encourage you to open two separate feature requests.
PS: There might also be an existing feature request that also “contains” your first request: Bitwarden Send - Enterprise Policy for all options