When you build your keyword sitemap within the platform, you are assigning your chosen keywords to your website landing pages.
Essentially, any page can be a landing page, and you can SEO them for specific keywords. Generally, we advise you use your 'evergreen' product/service pages for SEO.
You can use blog pages for SEO, but you need to be careful what keywords you optimise on them. You want to make sure that Google does in fact rank blog pages for that keyword at the moment.
For example, if I want to rank for the keyword "best SEO tool" I should go to Google and search this phrase. If Google is showing blog pages as some of the top results then I could optimise that keyword on a blog.
But if Google isn't showing blogs as top results, then I would not look to optimise that keyword within a blog post.