Offset letter with internal closed shapes

I am trying to get my words bolder by using offset and creating multiple offsets of say 1 mm. This will be still fast in line print.
Certain letters (a, b, d, e, g, etc) have internal closed splines.
Offset only seems to offset the outer shape of the letter, not the inner shape. How to do this. In a letter ‘e’ I cannot select the inside shape to do a separate offset, I cannot ‘ungroup’ or ‘explode’ the letter.
Any suggestions please?