Ah. In that case…
The two big things that will affect laser burns are the burn speed and the laser strength.
Since you’re wanting to do greyscale, you can’t really just ‘increase’ the laser strength, so your only other option is to slow down the speed.
What power laser did you go with? I have used two, a 3w and a 7.5w. The 3w had to run at a pretty slow speed for most burns in wood to get a good darkness.
To some extent, the stepover will affect darkness too, but mostly only affects burn time. I think LightBurn likes to start with a .1mm stepover. Which looks really nice, but takes Forever to run. Most burns I do now I run at .2mm or .25mm stepover. Your laser strength can affect this too as more powerful lasers typically have a wider beam. You can get away with a slightly larger stepover.