Decorative seaming techniques?

I’m still fairly new to knitting. I’m currently knitting a baby blanket that will be small blocks sewn together. I want to seam them with a contrasting yarn for design. What technique will create a nice edge? I plan to do a blanket stitch along the edges of the blanket when finished, but I don’t think you can use blanket stitch as a seam. Any input would be great. Thanks!

A crochet stitch to join squares is always nice. Even if you’ve never crocheted, these joins are pretty straightforward to work.

and here at the very end.
Eunny Jang shows a baseball seam which is simpler and can be decorative at about the 5 minute point toward the end of this video.

One option I’ve been looking at to execute some new ideas is i-cord. Specifically a three-needle bind-off i-cord. (Multiple uses for i-cord on this page, unfortunately no pictures. Boo. -

You would probably need to pick up stitches along the edge of two squares to do the three-needle trick, which may be more work than is worth it for a whole blanket. But it would look pretty cool.