This is simple support
tiers.
Tier 0 are effectively secretaries who can file structured info around issue.
Tier 1 are dedicated support people who can follow scenarios and guide customers through the product.
Tier 2 are what you call "support engineers". They know the product, features, code, upcoming features and so on. For an in house product they are capable of making straightforward bugfixes.
Tier 3 is sometimes called "vendor support". For an in-house product this is effectively product development team.
As you can see, good supports bleeds into or blends with product development. This is how you get support answers like "this feature is planned to go live Y24Q1, but you can sign up to beta in exchange for feedback" or at least "This is not supported, but you can use features x and y to achieve similar result", instead of "Sorry, such workflow is not supported"