Generally email providers will provide these for you (i.e. O365, Google Workspace, etc.) If you self-host email then it's really up to you to set them. SPF is super easy, just read some docs on the syntax, then include all valid IPs that might send email on your behalf. DKIM is where it gets a bit tricky, as you need to generate keys and sign all you mail. This is assuming you WANT to send mail from those domains. If you do not wish to, then just follow what they show in this guide, or in one of the comments above.