How do I make a call to a collection?

ReadyAPI has a test step: ‘Run Test Case’
What’s the equivalent in Postman?

A few more details follow.

Instead of adding a 3 step login flow to every testcase, I’m looking to create a single collection with the same 3 step login flow, and reuse this login collection for all my tests.

I’ve been looking at setNextRequest(), but it has several downsides.

It only works in the scope of the active collection, so no calls to other collections.

It can’t be used for single request, ie. forcing me to use the collection runner which now has a limit even for my paid plan (major thumbs down).

I can do the entire thing in Powershell or JavaScript and run via pre-request script, but that defeats the entire purpose of using a dedicated API testing tool.