A buoyant comedy with a big heart follows a teen girl who meets her older self the summer before college.That summer before college can be strange, a moment suspended between life stages, and Elliott (Maisy Stella) is right in the thick of it. She’s turning 18 in the tiny picturesque community in Muskoka, Ontario, where her family has farmed cranberries for generations. She has a janky little motorboat, two best friends and a massive crush on the girl behind the counter at the local coffee shop. And she’s looking forward to heading to Toronto in a few short weeks to start the next chapter of her life.Sounds familiar. You might even relate. But “My Old Ass,” written and directed by Megan Park, does not go in expected coming-of-age directions. It’s as much about reframing middle-aged regrets as it is a story about youth, love and possibility — and thus the emotional heft it wields is two-pronged.Elliott belongs to a newish and very welcome variety of teen girl movie protagonist. For decades, these characters were mostly siloed into vapid types, the better for us, I guess, to “understand” them: Goths, cheerleaders, ditzes, bookish wallflowers, cool girls, bullies. Elliott, on the other hand, is funny, capable and comfortable in her own skin. She can drive a tractor and steer a boat, and also forgets to show up for her own birthday dinner with her family. She is very thoroughly 18, with as strong a sense of self as you can really have at that age, while also being kind of a jerk at times to her parents and brothers. She loves them. She just finds them kind of annoying, though she’s not above apologizing for her behavior.Elliott’s characteristics aren’t markers of being a Strong Female Lead so much as just an actual teen girl, the kind you probably know, or maybe were. I found myself thinking of various characters played by stellar young actresses in recent films: Haley Lu Richardson in “The Edge of Seventeen,” Emilia Jones in “Coda,” Lily Collias in “Good One,” Saoirse Ronan in “Lady Bird.”With this complexity in mind, it makes sense that on Elliott’s 18th birthday, she and her friends Ro (Kerrice Brooks) and Ruthie (Maddie Ziegler) decide, with age-appropriate recklessness, that it’s time to have a transcendent experience. They obtain psychedelic mushrooms and head to a little wooded island to camp out and experience their trips, whatever they might be like. Elliott is at first disappointed that the shrooms don’t seem to have any effect on her, but then the unimaginable occurs: Her older self suddenly appears at the campfire. (You see now where the film’s title comes from.) Elliott at age 39 (Aubrey Plaza) is a Ph.D. student and, perhaps relatedly, more cynical than she was as a teenager. But she seems delighted to meet her younger self, and offers a load of advice, including warnings to stay away from someone named Chad who might turn up soon. And though the mushrooms wear off, the connection between younger and older self outlasts the drugs’ effect, to both Elliotts’ surprise.We are having trouble retrieving the article content.Please enable JavaScript in your browser settings.Thank you for your patience while we verify access. If you are in Reader mode please exit and log into your Times account, or subscribe for all of The Times.Thank you for your patience while we verify access.Already a subscriber? Log in.Want all of The Times? Subscribe. More