Summon Villagers with Villager Data

Master Rank Villagers do not spawn with full chain of trades while using:

/summon villager ~ ~1 ~ {VillagerData:{profession:farmer,level:5,type:plains}}

 

They only spawn with trades that become unlocked at the specific level they unlock it at. Instead of a Novice Rank villager being traded with and ranked up to Master Rank villager and getting all the trades.