Hi there,
Your blog page is just a normal static page with entries in it. What you’re referring is masonry layout, which is of course default to both portfolio and blog home page.
What you need to do is go to Admin > Settings > Reading > Front page displays and set your Posts page to your blog page. Then go to customizer’s setting and change your blog layout to masonry.
Please note that Blog doesn’t have the filter like the portfolio, except if you’re on Ethos stack.
No need to modify the template, masonry and posts are part of blog templates. The only problem of your current setup is that your blog page is static (not actual blog page).
Thanks!