If you've never done an ironing test on the Centauri Carbon, it's actually worth playing around with. Ironing is one of those settings where a tiny adjustment can make a pretty noticeable difference, especially on prints with a big flat top surface.
Basically, ironing makes the nozzle go back over the finished top layer and push out a very small amount of filament. It's almost like the printer is smoothing over the top of the print one last time. When you get it dialed in, those normal top-layer lines can almost disappear.
For my Centauri Carbon ironing test, I'd start around 25 mm/s ironing speed, 10% ironing flow, and 0.1mm line spacing. Don't take those as perfect settings for every filament though. Think of them more as a starting point and adjust from there.
The easiest way to test this is with a small flat ironing calibration model. There's really no reason to waste a bunch of filament testing this on a huge print. Print a simple flat test piece, look at the top surface, change one setting, and run it again.
I'd start by adjusting the ironing flow. If you can still clearly see gaps between the lines, try increasing the flow a couple percent. If you're getting rough areas or little ridges of excess plastic, you've probably gone too far and should bring the flow back down.
Speed is another one worth experimenting with. Slower isn't automatically better. Going really slow can actually give the nozzle more time to heat and move the plastic around. I like starting around 25 mm/s and making small adjustments from there.
I'd also test this using the filament you actually print with. A Centauri Carbon ironing test you dialed in perfectly with one spool of PLA might not look exactly the same when you switch brands, materials, temperatures, or even colors.
Once you find that sweet spot, save the settings to your filament or slicer profile. That's really the whole point of doing an ironing test. Spend a little time dialing it in once, and then whenever you have a print with a big visible top surface, you already have settings that you know look good.