Sounds like you would want to do a total conversion mod, and you would probably want to remap the engrams to your own custom engrams.
There is no way currently without making your own graph system to have an engram branch, where a player can choose to learn only one tier of crafting.
A short cut method, would be to create a new engram system. In this new engram system to learn how to make cloth pants you need to learn Beginner Armorsmith (150 engram points) And you would make them need to learn all the armor pieces of cloth to learn the new Trainee Armorsmith (225 engram points) This tier will let them learn all of the leather tier. And you would continue to do this, for all tiers, making it overall cost 2000 engrams to learn all the armor.
While this system can be circumvented by most cheaty servers, that allow players to have 50,000 engrams. There are some servers out there that play with relatively normal settings, you won’t find too many though =p.
Alternatively you would need to actually disable engrams and engram points, and create your own graph node system. That would store in ini files or the stramid profile file in the arksave folder, data about what tier they purchased, and disable other tiers. You would basically be reinventing the wheel, but you don’t have access to the wheel to prevent a player learning everything otherwise. It would be good if the engram class had an additional field “engram requires not to learn sets” but we don’t have access to modify the core blueprints with the ADK