You can make a story like that a "change of life" story for your MC. "Coming of age" is just one kind of change of life, there are others, they all just mean she comes to a new understanding of life due to the events in the story.
In other words these subplots influence her thinking, she comes to understand people and life differently. So that by the end, their collective influence has changed her in some significant way. She falls in love, or out of love, she loses her faith in somebody else, or in her religion. She stops being subordinate to her father, or mother. In some way, the reader knows she and her life won't be the same.
Your only problem is that whatever is driving her to complete her quest must seem to the reader compelling enough for her to make the journey in the first place; this must be a journey she cannot let go.
Recall Dorothy in The Wizard of Oz, pretty much the whole story is sub-stories about the Scarecrow, the Tin Man, the Cowardly Lion, the Wicked Witch and the Wizard himself. But Dorothy is compelled to make her journey and perform her tasks, it is the only way she can get home. In the end getting home is a pretty trivial and anti-climactic exercise. IMO, because she already had her ruby slippers from the start, so her journey, encounters, battle and uncovering the fraud of the Wizard were all unnecessary!
However, they were necessary to change Dorothy into a different person.
When she succeeds, she is a changed girl, with renewed love for her family. It isn't a coming of age story, there is no romantic or sexual component and Dorothy has not become a woman in any sense; but it is a change of life story for Dorothy. She has been a leader, a problem solver, a hero, she has been brave and attacked and killed the evil witch to save her friends.
In this approach your story can have a real false climax, when your MC saves her family, but the true climax of the story follows that: the MC revealing how she has changed, at least to the reader, perhaps to the family that knows her. She can make a dramatic life decision (after being influenced by her adventures): "I won't marry Tom", or "Sorry Dad, I'm switching my major from medicine to engineering." Basically something about the trip has caused her to assert her independence and control of her life, so she asserts independence in making a life decision for herself, without needing to please her parents or family or anyone else. She can love them without having to listen to them!
If you look at your story in this light, you might be able to ferret out some transformation your MC can be undergoing, and then tweak your scenes and subplots so she is being nudged in each scene along the path of this transformation (as revealed in her thoughts and actions).
If you choose this route, this definitely becomes a "Character driven" story which can happen in any genre; and your scenes should all be told through the eyes of your MC. That is the character we want to see thinking, being troubled and questioning what they know and changing her mind. She is the one the reader should love, so in the end the reader understands and is glad for her success, not just in saving her family, but for her success in finding her true self.