Yes, that sounds right.
If in doubt draw the individual squares and hsts onto paper, subtract the seam allowances and measure, then re-draw them 3 times as big, then add seam allowances.
If the original block is 12" x 12" finished size then there are 3 light blue squares in the corners which are 3" x 3" finished, or 3.5" x 3.5" cut.
Subtract seam allowances from cut size; 3.5" - 0.5" = 3"
Multipy by 3; 9"
Add seam allowances: 9" + 0.5" = 9.5" cut size.
The pale blue and yellow hsts on the edge of the block which make up a 3" x 3" square:
Hsts are cut from a square 7/8" bigger than the finished size.
So for those make the divided square 3 times bigger = 9" x 9" and add 7/8" - 9 7/8" x 9 7/8"
Or make them a bit bigger and trim down to 9.5" x 9.5"
It will work the same with the smaller pieces.
Calculate the finished size and add seam allowances.