Patrick Schwarzenegger is no shrinking violet. How could he be? Son of Arnold, the Terminator, and Maria Shriver, a journalist and member of the Kennedy dynasty, the 26-year-old was a ball of energy on the set of “Daniel Isn’t Real,” the horror film he stars in that’s out this week.

“I’m very much an extrovert,” says the former teen model, who plays the titular imaginary friend of troubled college student Luke (Miles Robbins). “If you ask people in the cast — especially Miles — he probably was annoyed with me at least some of the time,” Schwarzenegger tells The Post. “I was always strutting around and playing pranks. We had a great time.”

The strutting, Schwarzenegger says, was part of getting into character. “Daniel Isn’t Real” called for an over-the-top performance as an evil embodiment of toxic masculinity. Though Schwarzenegger says he’s not really a horror-show kind of guy, he was drawn to it by one of the kings of over-the-top performances: “I love Nic Cage,” he says. When he got the script for “Daniel,” he was told it was from the producers behind “Mandy,” Cage’s 2018 indie horror film, “so I was really excited to work with them.”

The creepy thriller was shot in Brooklyn Heights, Greenpoint and Staten Island, but Schwarzenegger, who lives in Los Angeles, says he resisted the siren song of New York’s nightlife while shooting. “I like to keep it low-key,” he says. “Manhattan is around the corner, and I didn’t want that to be a distraction. I like to just be with the people who are part of the film.”

Eight years ago, when Schwarzenegger was still in high school, he co-founded a philanthropic clothing line called Project 360, which donates a percentage of every item sold to help victims of domestic violence, fund Alzheimer’s research and other charities. A fashionista himself, it’s no surprise he was hands-on with Daniel’s look. “Day 1, when I got there, we dyed my hair black, my eyebrows really black,” he says. “And then they let me go shopping with the costume designer. Daniel is a guy with swagger. We wanted to make sure he was a complete contrast to Luke, who’s always in T-shirts and straggly jeans.”

Despite his uber-famous and occasionally infamous family — he has a 22-year-old half brother from his father’s affair with their housekeeper — Schwarzenegger has described his upbringing as “normal.” His parents encouraged him to go to college rather than jump straight into a career, and in 2016 he graduated from the USC Marshall School of Business. It seemed a logical step for an enterprising young man who, in 2014, invested in a Blaze Pizza franchise, opening a restaurant in the Grove mall in LA, on campus at USC and at the Staples Center.

Thanks to his father, he spent much of his early childhood on movie sets, soaking up Hollywood via some of the biggest blockbusters of the last century, the “Terminator” movies among them. “Daniel” is his seventh feature film; he had his first leading role in 2018’s “Midnight Sun,” opposite Bella Thorne.

He says the main thing he learned from his father was the importance of teamwork. “One thing my dad always taught me was that a movie isn’t just about the actors,” Schwarzenegger says. “There are hundreds of people on a set. There are the people who do transportation, who get you to the set. There are the people who do hair and makeup, who make you feel like the character. So on my dad’s films, it was important to him to get to know the whole crew. Not to just go into your trailer — to get to know each and every person there.”

Even so, he balked at his dad’s dedication to bodybuilding. “Do I like working out? Yeah,” the younger Schwarzenegger told the LA Times last year. “Do I like being healthy and drinking green juice? Yeah. But do I want to have big muscles and be huge? No, I’m OK.”

He’s found another role model in Amy Poehler, who’s directing “Moxie,” the comedy he’s filming now. “She was telling me how she loves to become friends with people on set,” he says. “She’s always coming around on breaks, hanging around with the actors, asking if they need help and just asking about their lives. She likes to make the set enjoyable.”

He says he’s looking forward to celebrating Christmas with his clan, including his girlfriend of two years, model Abby Champion (he and Miley Cyrus were an item for five months before breaking up in 2015). His new brother-in-law Chris Pratt, who recently married Patrick’s older sister Katherine, will be there, too.

“My family is an extremely close-knit group,” says Eunice Kennedy Shriver’s grandson. “We spend the day before Christmas at the church, doing a clothing drive and meal giveaway to people who are less fortunate. That aspect of giving back, and giving together as a family — that’s what makes it really enjoyable.”