In some cases, a heel that is too high can be cut down. That method works best if you're looking for a minor height adjustment of half an inch or so. Any more than that and your cobbler will most likely replace the entire heel block with a shorter version.
Happy with the heel height, but prefer a different silhouette? A stiletto-type heel, for example, can be replaced with a chunkier version, or a thicker heel swapped for a slimmer one. Leather heels, which are dressier, can be changed to more casual stack heels and vice versa.
Going lower or changing the heel type is easier. Whether you can switch to a higher heel depends on the boot's arch.
Ask your shoe repair professional to show you the types of heels available and explain which would work best with your boots given the amount of wear you'll be putting on them.
Your shoemaker can also replace plastic heels with slip-resistant rubber; change heel tips from hard to non-skid rubber; and add heel savers to prolong the life of the heel.