They may be specified but that doesn’t mean they’re necessary. An Iridium or Platinum plug will not perform one bit better than a regular copper core plug.
The only thing the Iridiums and Platinums have going for them over the copper core is that, on average, they may last a bit longer. As far as performance and fuel mileage it’s a wash.
Car makers started going to Platinum/Iridium because the Feds required them to cover spark plugs for the first 24k miles as part of the emissions warranty. Since the odds of a copper core misfire are greater than a Plat/Iridium plug misfire in the first 24k miles/2 year warranty they’re not taking any chances on having to replace millions of plugs under warranty.
Pricy out in the real world but on the assembly line those plugs are cheap.