The second block is a 7 x 7 block. On my screen the corner block measures 1 cm, and the middle block measures 1.5 cm, for a total of 3.5 cm across. That can easily be done as a 21" block, but for 20" you'd have to use decimals.
For a 21" block, the corners would be 6" squares finished (6.5" unfinished), the center top would be 12" wide (12.5 unfinished), but it's not a flying geese unit, I think I would need a template for this one. The center top is divided in thirds in both directions. Probably the easiest way to piece that piece would be to make a quarter square triangle block 12 " square, then cut off the part you don't need. The center square is a snowball unit. It would be 12" square (12.5 unfinished), with 4" finished (I think this would use 4.5" unfinished) squares sewn on the diagonal on each corner.
For 20" you're on your own.