Welcome to the forum!
AI is very expensive! And to my understanding, you can't even buy it outright anymore - only subscribe to it (which I would find outrageous as a user).
I've seen a couple of Inkscape extensions for making clothing patterns. But as far as I know, they don't work. (They may have once worked, but not anymore.)
I think absolutely Inkscape could be used to make or edit patterns. But if there is some dedicated software somewhere, you might find it more convenient. For example, it probably has a lot of customized features, such as placing the diamond notches that are used to align different pieces for sewing, or other special symbols. Or like for adjusting the pattern to different sizes (which can't be done by simply scaling the whole pattern larger or smaller).
The good news is that you can easily test it out, if you want to edit exising patterns. Just install Inkscape, and open one of the SVG files