The major league Mets are about to grow bigger — and more interesting.

Highly touted prospect Ronny Mauricio will be called up when rosters expand Friday, The Post’s Joel Sherman reported Wednesday night.

The 22-year-old does not have a solid position but does have an intriguing bat. The switch-hitter entered play Wednesday with an .860 OPS and 23 home runs, plus 24 steals, in his first 115 games at Triple-A Syracuse.

He always has been a free swinger, though he has shown better plate discipline this season with a slightly improved walk rate (6.6 percent) and a slightly lowered strikeout rate (18.2 percent).

But the natural shortstop has not found a second position that he plays consistently well.

With Francisco Lindor blocking the path at short, the Mets have moved Mauricio around without a ton of success.

The reports were not strong at second base, a position he began playing in late April, and he moved to both third base and left field with similar results.

For the past two weeks, Mauricio has shifted back to second base, where manager Buck Showalter said he “seems to be doing well.”

Showalter said that while Mauricio has handled the spot better the second time around, he made it clear that defense is what has held him back.

“Defense is initially a priority with these guys,” Showalter said from Citi Field before the Mets finished a series with the Rangers. “Got to be able to defend.

“You got to hit a whole lot to not be a good defender.”

The Mets surely hope Mauricio will hit plenty.

The club was planning on meeting Thursday to discuss its options for Friday when a 26-man roster becomes a 28-man roster.

Showalter allowed that both Mauricio and Brett Baty were “under consideration,” and the decision now has been made.

Even without a definite position, there is an argument that Mauricio — who is already on the 40-man roster and is the organization’s No. 4 prospect, according to MLB Pipeline — should be learning second base in the majors.

Danny Mendick and Jonathan Arauz, who do not figure to have long Mets futures, have received plenty of time at second since the Mets sold at the trade deadline.

Until this point at least, the Mets had not shown a willingness to test out Mauricio’s toolsy game without more certainty of his glove.

Presuming the Mets select from players on their 40-man roster, their pitching options for a call-up are less intriguing. Joey Lucchesi or Grant Hartwig could return to Queens.