Show posts from a single category by default using wordpress.com

I have a blog at wordpress.com on the legacy Personal plan. I blog about different but related subjects and categorise the posts accordingly. The blog was originally about one subject but, over time, the content diverged. One subject is more generally accessible while the second is more specialized.

When someone visits my blog, can it show posts only from the more general category by default? For example, I could create a new page containing the Blog Posts block to show blog posts filtered by a category. However, it only shows the title and first 55 words by default. I am happy to code but wordpress.com, even using the code editor, does not make it easy.