As the titular star of Ridley Scott’s epic 24-years-later sequel “Gladiator II,” Ireland’s Paul Mescal leaps from his position as an indie film stalwart to global recognition.

As he noted Monday at a virtual press conference in Los Angleles, it’s been a series of remarkable career leaps.

“Two years ago was an Oscar nomination” – as Best Supporting Actor for the rueful father-daughter drama “Aftersun.” “Last year was ‘Streetcar’ ” – a hit London stage revival of ‘A Streetcar Named Desire’ which won him an Olivier Award and which he reprises this winter in London and New York. “Now this year it’s ‘Gladiator II.’ ”

As the star of a $200 million production comes the immense responsibility that decrees you set the tone. All eyes are upon you, every minute of every day, for months.

“Ridley doesn’t wait around. He let me know what we were stepping into the first day, which was the Morocco sequence that opens the film.

“I was walking around with my sword, smoking, waiting to be summoned to the set. Ridley is smoking a cigar, looks at us and goes, ‘Are you nervous?’ and I just made a noise. And he said, ‘Your nerves are no (expletive) good to me’ – and that was the first time I saw the scale we were dealing with.

“I saw it as, ‘This is where you’re going to live for the next days. It explained everything. This is the scale and there is the world he builds.”

Essential for “Gladiator II” is the physicality. Mescal, 28, trained for six months to build himself up. Then, after a break, return many pounds lighter.

“Weirdly, the act of leading a film,” he realized, wasn’t unusual. “I grew up playing sports and was captain of my school football team, so that position isn’t alien to me. It’s just multiplied by 100 on a Ridley Scott set.

“To me a set is practical thing: it’s something you can control. The minute you get in front of a camera, you have to take up the space you want to occupy. Whatever I’ve learned from sport I take that from there.

“I was keeping all that muscle on and then after filming, I went to shoot ‘The History of Sound.’ Over seven weeks I lost 10 kilos. So the last two weeks of the ‘Gladiator’ shoot, the poor trainer saw me not in the best form.

“That,” he said cheerfully, “was the hardest part of it. I saw more of my trainer than my family last year.

“People who are part of your team are so important,” he learned. “It’s that they have to know you fundamentally and you have to trust them – and I found one of the good guys.”

“Gladiator II” opens Nov. 22