When you’re in a FaceTime call, you can share the link with others so they can join. Although FaceTime is an Apple-exclusive application, you'll even be able to send the link to people who don’t have an Apple device.
How to invite anyone to FaceTime on iPhone
Go to the FaceTime App
Tap Create Link at the top of the screen
Choose an option for sending the link (Messages, Mail, etc.)
This also works for those on a web browser, and no login is necessary.
How to invite anyone to FaceTime on Mac
In the FaceTime app on your Mac during a video call, click the Sidebar button, then click Share Link
Choose how you want to share the link