In almost the same fashion of using color in film, special effects in movies are an innovative way of visualizing storytelling elements that may or may not be diegetic to the world that the film is set in. They can help with further pushing the narrative of the story that is being told, as well as utilize the storytelling narrative of “show, don’t tell”.
One example of a show that uses these diegesis special effects is the Marvel show “WandaVision”.
Spoilers for the show (from what I read on different websites, and breakdowns I’ve listened to on YouTube, because I simply cannot just sit down and watch a show) starting now:
WandaVision is a show that aired in 2021, and takes place…sort of all over the place, and within the same space at the same time. Wanda Maximoff (Scarlet Witch), grieving the loss of her husband, Vision, creates an entire universe within the radial space of where her and Vision were supposed to live before the events of Infinity War and Endgame happen. She traps multiple people under her control, which cause them suffering, within a universe where everyone takes on a role within a televised show, which is also called WandaVision. Under her intense grief, she is able to “revive” (manifest a new version of) Vision, and live with him as his wife under the pretense that they are the main stars of their own sitcom.
After certain events happen that break the immersion of the set of WandaVision, Wanda takes her and Vision, and the rest of the “crew”, through time into another decade, where the illusion resets and a new episode (within that reality, within the reality of that reality, and within our reality) airs with everyone in a new decade. With each beginning of a new episode, a different opening is played that fits within the era the sitcom is set in.
The video above this displays this, with the first opening starting in a setting fitting of a sitcom set between the 50s and 60s; then it follows to a different and later version of a 60s sitcom with a cartoon opening; the first opening to be in color, and the third opening of the show, is set in the 70s; skipping to episode 5 of the show, WandaVision now appears to be in-between the 80s and 90s in a Full House style opening; the next opening is one fitting for the early 2000s; and the final opening is set in the late 2000s similar to The Office, with the title screen reminiscing romcoms and romantic movies of that era. The added Agatha All Along “opening” happens in episode 7, and is also meant to play as its own diegetic storytelling element, as it reveals that she was the one controlling all of the chaos that happens on screen to throw Wanda off and get to her to figure out how she is doing all of this.
With each new era that they are set in, the special effects used within each episode change to fit special effects that would be used for that era. For example, in the very first episode, WandaVision utilizes the practice of simple practical effects, as well as simple editing for things that they couldn’t showcase practically.
While the entirety of that show relies on the usage of special effects to tell its story because of the concept and story behind it, it is also a good example of how much special effects can be used in storytelling as a tool just as much as the actors and music itself.