When it comes to themes and SEO, all we can really do is make sure things are light and fast, which is why we focus so much on that area. The results are based more on your content and the current algorithm that Google is using.
I’m not sure if using breadcrumbs would actually “optimize” SEO for your site. You’d need to check with Yoast’s support.
We don’t really have a specific recommendation for an SEO plugin. We use Yoast in our site but have heard good words for RankMath as well.