well for the sea urchin i use medibang paint's effects options
from there it's just a matter or messing around with the slider options till you get something you like
spaces can be filled in with a brush and then resizing to your needs for the panel or just select the space from the start and medibang creates the pattern in just that spot.
as for medibang it's a free software and it's worked alright for me for the past few years. it's not as robust as clip studio/manga studio but get's the job done. Link's here:
as for those cartoon style bubbles i just do my best in just drawing it by hand. it doesn't always come out perfect but something that's kind of helped is having a guideline below it in the size or shape your looking for. I did these real quick as an example but it gives a gist of a sort of process
big things to remember is not to bother too much with making it look perfect, so long as the points clear it should be good. also the varied rings can help determine variations in the curves and spiky bits to kind of give it a more "wild" or excited feel depending on the balloon.
hope this helps