Doing a manual engrave gives the option for multiple passes. I have used that to achieve a deep engrave on 1/4" that turned out well. As long as the work is not moved, you can also run the file again, so you can get unlimited passes that way.
Tip to bear in mind is engraving closest to the light source tends to slightly ‘shade’ engraving above it, so it’s best to do shallow closest to the light, and go deeper as the design progresses further from the light so all of the engrave catches the light and it is evenly lit.