Yes... and no. Manufacturers have kept the set gap from the factory much more consistent than in years past, but I never assume they are good to go and double check my new plugs before installation.
You may have noticed quality plugs now use a plastic sleeve not just to protect the threads but to maintain the gap between the central electrode and side electrode (ground).

But it is important to be aware manufacturers of iridium plugs discourage manual gapping for fear of damaging the iridium coating on the central electrode. Platinum used to be the magic metal for sparkplug longevity but now iridium is the metal of choice and is 6 times stronger and 8 times harder. It's also even more expensive, so the central "pin" on your iridium plug is just coated with the stuff. Scratch that thin coating and that pin will melt like a cheap birthday candle on a hot day. So proceed with caution. :nod:

To the OP, stock gap is fine on your car with minimal mods. Your tuner is being conservative as he doesn’t want to chase his tail with potential misfires but there’s no reason for you to have any with your mod list.

Under boost, I’d start at .035” at low boost (~6 psi or so) and start tightening it up the more boost you make. I’m at .028” with 16+ psi.

I'm at .028 but .025 is likely better for me. Pretty sure that's what KaTech uses. But these tight gaps make for very rough idles.

Richard Holdener posted a YouTube dyno video about spark plug gap. He ran from .010" to .100" on a stock GM 5.3-liter engine. The .100" gap made 5-6 more horsepower than the smaller .010" gap.

Here's the video link: https://youtu.be/_6qzd08D7ow

I run mine in my maggie 2650 at 15psi .040. I have the 6510s. They are pregapped at .040 and I run those with MSD wires. No issues, no misfires.