You can make the strips any size.
The square will grow, depending on the size of the original two strips.
2.5" strips will probably produce a square that would measure 4 and 5/8ths inch.
If you want to make a bigger block, then try cutting beginning four inch strips ... the resulting 2-strip piece would measure 7.5" ... finished size of the square would be 6.75" give or take an eighth of an inch ...
The table topper is terrific, too!
Good show! <wave>