In fanfiction, anything can be possible. Morgan Stark bringing Tony Stark back could be achieved through various means. Maybe she discovers some advanced technology her father left behind that has the power to reverse time or bring someone back from the dead in a scientific way. It could also be something more magical or otherworldly if the fanfic takes a more fantastical turn.
Common themes include the bond of family, which is shown through their daily interactions, like Tony reading bedtime stories to Morgan. The theme of mentorship also pops up, as Tony imparts his knowledge and skills to Morgan. Additionally, there is often the theme of loss and remembrance, as in how Morgan copes with the loss of her father and how she keeps his memory alive in different ways in the fanfics.
There is a fanfic where Morgan Stark time - travels back to the early days of the Avengers. She has to adapt to the different time period while also trying to prevent a major disaster that she knows is going to happen in the future. This concept allows for interesting interactions between Morgan and the original Avengers members, and it shows how she can hold her own even in a different era.
In a time travel fanfiction involving Morgan Stark, perhaps she travels back in time to a crucial moment in her father's life, like the battle of New York. She uses her knowledge from the future to help him, but also has to be careful not to disrupt the timeline too much. Morgan might end up forging a new bond with her father that was different from the one she had in her own time.
Well, in some fanfictions, Morgan might hate Peter because she could be jealous of the attention he gets from the other Avengers or people around them. Maybe she feels that Peter is taking away the spotlight from her or her family in some way.
There is a fanfic that focuses on Morgan Stark's relationship with her mother, Pepper Potts. Pepper tells her stories about Tony Stark, and these stories inspire Morgan to take on a project to revive an old Avengers project. Along the way, she meets different characters from the Avengers universe, and the story is as much about family and legacy as it is about the action and adventure in the Avengers world.
Yes, there are many. You can start by looking on fanfiction.net or Archive of Our Own. Some fanfictions might focus on their friendship growing in the post - Endgame world, where they support each other through the losses they've faced.
One common theme is family. Since Peter is sort of like an adopted part of the Stark family, many fanfictions explore how he and Morgan form a brother - sister like bond. It often shows them supporting each other through difficult times.