What is the standard for UIViewController transitions?

What is the standard for the transition between UIViewControllers in swift4xcode10?
When I looked into it, I found that many of them connected segue from the xcode storyboard GUI... and that it was difficult to find a purely code-only implementation, and that there were some implementations that fit my purpose.

I think the transition method will change according to the precondition.
As an idea,

1. The pattern where the transition source UIVC becomes the parent and returns to the parent when the child has finished processing. 2. Discard the transition source UIVC, and the transition destination becomes the main UIVC

Are there any other prerequisites for 1 or 2?Also, please let me know if there are any standard or convenient methods for each transition.
I would like to know how to implement only the code in principle.

It may change a little, but is it possible to define the relationship between UIVCs by defining the segue with the code?