Alexis Mac Allister is a player who just plays well in the PL but without any fuss or hype around him, interesting option for midfield but not sure if he will start.
Even if they start De Paul and Fernandez ahead of Paredes (though Fernandez only has the 3 caps) in knockout games, you have to like Mac Allister in the group stages against some weaker teams where you need a bit of magic, and to come off the bench in knockouts. You figure Messi and Lautaro will mostly play 90 but left-wing will be a place to sub and then Mac Allister and maybe the fairly interchangeable fullbacks would be the next obvious sub spots.
So yeah, he may not start but he's a fun choice for the best sub of the tournament along with:
-Alvarez also for Argentina
-Fullkrug if Germany need a 9 can come on and score in a couple games and be a cult hero
-Nico Williams in the Jesus Navas role as a Spanish winger who can come on and beat a man and get crosses in when they're dominating but not dangerous
-Suarez or Cavani
-Multiple Japanese attackers really if they can shockingly get past Germany or Spain to finish 2nd in that group
-Richarlison just has multiple late goals off the bench written all over him
-Majer on Croatia is supposed to be mint and might not start
-Coman as similar to Nico Williams as a traditional winger to unlock a game
-Gapko or Xavi Simons if Van Gaal starts the Bergs (wijn and huis) next to Memphis in attack and they play like the decent but not world class players they are.