The blocks in my Pinky The Piggy Blanket are joined using the Join-As-You-Go technique, where each block is made individually and joined to the previous blocks with sl sts while working the last round. So, you can easily add or omit blocks if you want to make a different size.
Here is a short video to demonstrate this technique:
Join-As-You-Go for Basic Granny Squares
Finish your first motif as normal. For the remaining motifs, join them as you go to the previously made motif(s) while working the joining round as follows:
Begin the row/rnd as described in the pattern and work to the corner where you need to start joining; work in corner — 3 dc, *ch 1, sl st into corresponding corner of the previously made square, ch 1, 3 dc in same corner**, [sl st into corresponding sp of the previously made motif, skip 3 sts, 3 dc in next sp] to next corner; repeat from * to **. Continue to work around the remaining sides of the motif in pattern as established, ending the rnd as described in the pattern.
You can also check out my other tutorials for Joining-As-You-Go: