We’re days from the official opening of the NCAA transfer portal, and if there’s one thing we’ve learned from the magical addition to college football, it’s this: Think big.

Think big, and look far and wide. Because one player can change everything.

Michael Penix. Jaxson Dart. Jared Verse. Jayden Daniels.

And Caleb Williams.

“I don’t know how any coach can see what happened this year and think the portal isn’t your friend,” a Power 5 coach told me. “We’ve all complained about it. But you’ve got teams battling for the Playoff who were either built with (the portal), or supplemented by it.”

Or impacted by losing out on a player in it. Case in point: USC QB Caleb Williams.

The improbable rebuild under first-year Trojans coach Lincoln Riley isn’t just about the double-digit impact players he convinced to join a team that won 4 games in 2021 — and a year later is 1 game from the Playoff.

It’s about how 1 player can change not just 1 program — but impact the fortunes of many others with a decision.

Williams was the No. 1 player in the 2022 transfer portal and left Oklahoma after his freshman season and after Riley left for USC. Williams then methodically went through a second recruiting process to find his next school, and chose USC.

He was also considering Georgia and Wisconsin, and that’s what makes the portal so potentially devastating with collateral damage.

Think about the butterfly effects with these what-ifs:

— If Williams doesn’t choose USC, the Trojans aren’t playing in the Pac-12 Championship Game on Friday against Utah with a chance to reach the Playoff.

It’s not a stretch to say redshirt freshman backup QB Miller Moss, with 27 career attempts, isn’t leading the Trojans to the Playoff. Or maybe he is.

Maybe Moss — the No. 76 overall prospect in the 2021 247Sports composite — would’ve developed into an elite quarterback under Riley. Who hasn’t?

Baker Mayfield, Kyler Murray, Jalen Hurts, Spencer Rattler and Williams all did. Moss may have fit right in line — and then maybe he’s be headed to New York City for the Heisman Trophy ceremony instead of Williams.

Or maybe All-American wideout Jordan Addison doesn’t sign with USC 3 months later. Maybe Wyoming transfer DE Solomon Byrd, a force off the edge in pass rush situations, doesn’t transfer late, too.

Maybe it’s a completely different rebuild at USC.

— If Williams chose Georgia, the Bulldogs are still the unquestioned best team in the country — but could be staring at an unprecedented 3-year championship run.

Williams still has 1 year of eligibility remaining after this season, and Georgia’s roster is littered with underclassmen. The idea of 3 straight national titles not only would’ve been a very real possibility, but more than likely a high probability.

How impressive is that? There has never been a 3-peat national champion in the history of the Associated Press Poll, which began in 1936.

But that’s not all. Williams is 1 of 3 Heisman Trophy favorites and would be a lock as the quarterback of the No. 1 team in the nation, especially with similar numbers in the best conference in college football.

— If Williams chose Georgia, current starting quarterback Stetson Bennett — who is 3 victories from becoming the first quarterback since AJ McCarron (2011-12) to win back-to-back national titles — would be playing elsewhere this season.

Bennett delayed his announcement to return to Georgia because he wanted assurances that Dawgs coach Kirby Smart was committed to giving him the ability to compete for the starting spot — should JT Daniels stay and Georgia sign Williams.

Bennett announced he would return to Georgia on Jan. 19, and Williams announced he would sign with USC 2 weeks later. Daniels eventually transferred to West Virginia.

Had Williams picked Georgia, it would’ve been clear early in spring practice that Bennett wasn’t going to play, and he would’ve transferred — forever to be remembered by his meteoric 2021 season.

— If Williams chose Wisconsin, the Graham Mertz era in Madison is over and Paul Chryst is still the Wisconsin coach (and Luke Fickell is still the Cincinnati coach).

With Williams (and not the inconsistent Mertz) as his starting quarterback, Chryst and the Badgers lose once (probably) to Ohio State. The rest of a highly manageable schedule is navigated, and the 11-1 Badgers are playing Michigan in the Big Ten Championship Game to get to the Playoff.

Wisconsin has the No. 13 total defense in the nation but is 91st in total offense with Mertz in his 3rd season as starter. Williams would’ve changed everything offensively, and allowed talented WRs Chimere Dike and Skyler Bell to develop into elite receivers.

Williams was intrigued by Wisconsin because Chryst, while offensive coordinator of the Badgers in 2011, got Russell Wilson ready for the NFL. Williams patterns his game after Wilson, and 2 years of playing for (and being developed by) Chryst would’ve been 1 more than Wilson (an old-school graduate transfer — remember those? — from NC State).

Who knows how Williams’ game would’ve played out in the cold Madison Novembers, but the weather didn’t seem to faze Wilson — who chose Wisconsin because of Chryst, and because he knew he would eventually have to learn to play through inclement weather environments.

“More than 90 percent of the time, the portal is going to be about how quickly can you get me to the NFL?” another Power 5 coach told me.

How fitting. Because for coaches, it’s how quickly can you get me to the Playoff?

Sometimes, 1 elite player changes everything. For more than 1 team.