The honest answer
Google does not rank a site higher because of the platform it runs on. It reads the pages the platform produces. WordPress and Webflow can both produce pages that do well in search, and both can produce pages that do not.
The difference is where the work sits. Webflow is a hosted visual builder. It produces clean markup and has built-in fields for titles, descriptions and Open Graph. It also has 301 redirects, canonical tags and an automatic sitemap. Hosting is included in its paid site plans. You have fewer decisions to make, and you are tied to its platform.
WordPress is open source, and you host it yourself or with a host. Its plugin ecosystem is huge, and that includes SEO plugins that add the same fields. The result depends on your choices. The theme, the plugins and the hosting all affect how fast the pages load, and that shows in Core Web Vitals. WordPress also needs updates and maintenance.
So ask who will look after the site. If nobody will, a hosted builder removes that work. If you need something only a plugin offers, WordPress gives you more room. The lessons in the Technical SEO series apply to both. Whichever you choose, run a page through the free audit to see what it really outputs.
Features and plans change, so check each product's own site before you decide. For the cost, see the current pricing on each site.