Changing font thickness?

You can use Offset Shapes in the left toolbar. You will need to change the as typed font words into paths first; Edit>Convert to Path.
Then you can use Offset Shapes. You will need to experiment with each font and material to find out how to either do an Offset Shape outward or Offset Shape outward.
In the case of the insides of letters like: “e, o, p, q, b” you may want to offset outward the outer part of the letters, then inward offset the insides.