Technically, if you wanted to treat it to separate settings, you would need to include two separate engraves in the SVG file - one vectorized photo engrave for the “flag image”, at a low LPI and low power to prevent charring, and a separate deeper engrave for the text (so it would need to be a different colored fill) that you could increase the LPI on and burn it darker, after the flag had been rendered.
But it would take a lot of experimenting on scrap to make sure you had the flag part of the image rendering the correct “light” color for you - you only have two colors to work with in engraving - burned and not burned. Grayscales are just an optical illusion created by dithering, which is what the Photo Engrave settings do. (All the little dots you see.) If you treat the original as a Photo Engrave, you’ll get more widely spaced dots for the gray areas, and more tightly placed dots for the black areas. (More of a solid fill.)
You can experiment with both methods…and might wind up coming up with a new technique. I haven’t done anything like this yet, we’re just spitballing ideas here.