The Falcon and The Winter Soldier is the next canon series lined up in Phase Four of the Marvel Cinematic Universe after the peculiar series of WandaVision and a lot of questions are raised as to whether one would need to watch WandaVision first to fully understand The Falcon and The Winter Soldier.
WandaVision was a shocker to most fans and the whole MCU with the peculiarity of the series starting from sitcoms to a whole revelation of the origins of Wanda Maximoff and how she finally became the Scarlet Witch. WandaVision turns out to be a character-focused series on how the trauma and grief of Wanda brought out her powers more than what we had already seen before.
WandaVision proves that these series are not just canon, they are vital to the whole of MCU and it brings about the anchors that will solidify the upcoming films and series. It's the same with The Falcon and The Winter Soldier, it's preparatory for something bigger in the future and it lays down the roots of Phase Four just like WandaVision did.
However, the two series are standalone to one another, forming different parts of the MCU and laying different grounds in preparation for the groundwork of Phase 4. Without a doubt, WandaVision and The Falcon and the Winter Soldier are two different animals.
WandaVision is about Wanda Maximoff overcoming her grief resulting in the creation of a whole new reality which started as sitcoms and ended up with her acceptance of herself and of her fate, of who she is destined to be: The Scarlet Witch. It was a rollercoaster of emotions from the comedic sitcoms to the heart-wrenching reveal of the reason why Westview was created and to the discovery of Wanda about her real power.
On the other hand, The Falcon and the Winter Soldier is about Sam Wilson and Bucky Barnes taking on the mantle that Captain America has left after his retirement and how they would fill in the shoes that Cap left to carry on the legacy that the shield brings along, one Cap has fought for through the years: justice and what is right.
Just by looking at the plots, the two are heading in different directions: WandaVision is about grief and acceptance like a self-discovery of Wanda's character while The Falcon and the Winter Soldier is about stepping up to become the new Captain America. WandaVision is from the inside out while The Falcon and the Winter Soldier is from the outside that should transpire within.
WandaVision's progress is not the same as The Falcon and the Winter Soldier as well. WandaVision started mellow, just dropping hints as to what will ensure episode after the episode before the revelations and answers came out until the very end. As for The Falcon and the Winter Soldier, it is an action-packed series where the basis is already laid down.
It is also presumed that both happened within the same timeline or just a few days or weeks apart from each other and are far from coinciding. While both are set after the events of Avengers: Endgame, WandaVision made it clear it only happened immediately after; in The Falcon and the Winter Soldier, it is still unknown as to when exactly it happened (presumably it will be revealed through the series.)
So, does one need to watch WandaVision before The Falcon and the Winter Soldier? Even if it is not connected at first, it will all make sense in the end how everything is connected as it is like that in the MCU.
The answer is both a yes and a no.
Yes, you should watch WandaVision because it sets up various films that are ahead of the MCU as it gives the groundwork on the transformation of Wanda Maximoff to being the Scarlet Witch and the series has revealed so much about how it will be vital to Phase 4 of the MCU.
No, it's not a pre-requisite for The Falcon and the Winter Soldier as the two, as mentioned above, are two different animals, having two different concerns that are far from each other, having different agendas, and having characters that are distinct and unique to one another. You'll be able to understand The Falcon and the Winter Soldier, for sure, even without watching WandaVision.
Still, it's all up to you. Either way, both are under the same umbrella of the MCU and both are canon series so at one point or another, in the future, it will make sense how these differences could be patched together forming one whole universe like how the various Marvel films were before these Disney+ series.
The Falcon and The Winter Soldierpremieres on March 19, 2021, via Disney+.