A few short years later, the uncapped Melbourne City star, now 20, is on the verge of realising that dream.
Exuberant winger Younis has been the talk of the town since joining Melbourne City on loan from Brondby in January, catapulting himself into World Cup contention with eight goals and three assists across all competitions.
"Five, six years ago playing for New South Wales schools, I had written down that I want to make this World Cup, and play in the World Cup," Younis told AAP.
"Me and my brother were talking about it the other day. So it's always been a big, big dream of mine representing Australia and also (to get) my last name on the world stage.
"Representing your country is the highest honour in terms of football. I've represented every age group going up in football in Australia.
"So yeah, of course, it's something that in my heart I did have my eyes on, especially with all the noise recently, but I just try and stay level-headed and not think about it as much as I can."
Younis, a third-generation Australian of Lebanese descent, can lean on plenty of support from his sports-loving family.
His father Ray, a former NSL player, is the strength and conditioning boss at Western Sydney, where younger sister Talia stars for the A-League Women team. Younis's mother was a gymnast and his uncle Robert also played in the NSL.
"I'm very, very proud of who I am," former Western Sydney youth sensation Younis said.
At City, Younis looks up to his own hero in three-time World Cup attendee Mathew Leckie.
He also has the ideal mentor to help him navigate through life as a Socceroos bolter.
In 2018, Andrew Nabbout's breakout season at Newcastle caught the eye of then-Socceroos boss Bert van Marwijk ahead of the World Cup.
"Andy is obviously someone else who was a World Cup bolter, and he comes from Lebanese descent, so it's nice to have a sort of brother in the team," Younis said.
"He told me he hadn't been in any camp before and then when Ange Postecoglou left and the new coach came in, he got put into the pre-camp.
"And then things changed very quickly for him - he started against France. And what an achievement to say. He started against France in the World Cup and represented Australia as a number nine in such an important game.
"It's something that I can only look up to and dream of."
Bit by bit, Younis, who models his game on Leckie, Gareth Bale and Mohamed Salah, is getting closer to that dream.
Plenty of friends and family travelled to Melbourne for last Friday's loss to Adelaide, when Younis scored a terrific goal.
The winger marched over to them and celebrated with a "call me" celebration, seemingly referencing his desire for a call-up.
"To be honest, I shouldn't have done it," a sheepish Younis said with a laugh.
"It was a bit of peer pressure from my cousins and my friends who were there visiting me on the weekend. I apologise for that.
"But it's just exciting times for me. Everything's just going so fast. I'm really grateful for the things that have happened."
Younis knows the best way to impress Socceroos coach Tony Popovic is to perform in Saturday's elimination final against Auckland at Go Media Stadium.
Regardless of how selection plays out, Younis feels vindicated in taking a punt on returning to Australia to enjoy his football again.
"I wouldn't change a thing," he said.
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