I've been reading Leonie Morgan's '100 Colourful ripple stitches'. Some of the patterns are an unusual shape, and have no explanation of how to expand upon the pattern. One pattern repeat is given as, for example, 22cm (8.75inch) x 22cm (8.75inch), but how do I expand this into a much bigger afghan or blanket? See photo of the Arcade pattern in the book.
If you want to continue increasing a pattern worked in the round such as the one given, the key is to look for the pattern of increases in what's been given. The increases, where multiple stitches in a round are worked into a single stitch in the previous round, are what give the pattern its growth in each subsequent, larger round; I personally find them easiest to spot in a pattern diagram.
Most square patterns will have the increases primarily in the corners, and that's the case here as well; each corner of this pattern has you work 3DC into the stitch below it, on each side of the "turn." Additionally, the given pattern has some "petals" in the middle of each side, which have a pattern of their own; for two rows, you work 3DC into the center stitch of the previous round, then 5DC into the center stich, repeating that sequence as the petal grows.
You can use this process to increase any repetitive motif worked in the round to a larger size; this won't work as well if each round is distinct, as in some more elaborate projects.
The usual way to combine these 'squares' is to make many and stitch them together into a blanket.
In your irregular 'square' you may find they do not fit together well or at all in the usual pattern.
You can try out how the pieces fit together by cutting out a series of paper versions.
Select your pattern, make at least 10 realisticly shaped paper (or real) pieces and play around with them. Try using them at other angles as well. It may work to turn part of the pieces 45 degrees.
And do not forget that if you crochet them together you can make shorter or longer stitches, bridging bigger openings if needed.
And there is the option of combining 'squares' or different models. The one you show have points sticking out in the middle of the sides, there might be corresponding pieces which are having 'cut out' bits that would match.
Some blankets pieced together from crocheted pieces have bigger and smaller squares, it might be that there is a kind of matching piece in the book that is not obvious as the size is different.
And in the end, it is well possible that the writer of the book did ignore the 'making the blanket' as they did not intend these pieces to be actually used. Which does not stop you to be creative and still use them, but you will have to make your own matching pieces or filling connection patterns.
Alternatively, if you see a pattern in the expanding 'squares' you could keep expanding the single pattern till big enough to become a blanket by itself.