The Darkhold is seen in WandaVision, and it was previously seen in Runaways Season 3.

Xavin, a character from Runaways, is a part of the Xartan race, a subspecies of the Deviants, who were seen in Eternals.

In Agatha All Along, it's reinforced that there were multiple copies of the Darkhold before Wanda Maximoff destroyed them, which explains why the designs of Runaways and WandaVision were so different.

In the non-canon, Your Friendly Neighborhood Spider-Man, the appearance of Nico Minoru's parents is based on the Runaways series, as opposed to their looks in the comics.

Nico also believes in the Wiccan religion, a concept first associated with his character in the Runaways series.

In Runaways Season 3, the future versions of the protagonists travel through time—to be precise, they travel to the past—changing the past and altering their future. This type of time travel was also seen in Eyes Of Wakanda.