Square flower motifs are not only easy to make but also very easy to join. Depending on your body measurements the flower motifs can be multiplied or reduced especially in the case of a top or a blouse.
What is very important to keep in mind , is the fact that most flower motifs have certain point where they connect and this is very important in case you want to have a result that will fit you.
Another important aspect is the yarn and the hook. Bigger hook and thicker thread make a larger size. For a smaller hook and a very thin yarn simply multiply the number of motifs.
It helps to use a size pattern or a regula T-shirt to have an idea about the size.