You can create subdomains at your registrar (the service where you handle your domain) and link them to different Webflow projects. e.g. spain.yourdomain.com
Are you sure you can’t use the CMS to generate your landng pages (you’d input titles, texts, images and so on), use a Slug field to control your URL (so that each CMS page can be served by a URL like yourdomain.com/country/spain
You can design various section on your landing pages, and for each landing page, set data for each of the different designs, then use conditional visibility to hide and show sections depending on their data is set or not. This way, your landings can have different design, depending on what they need. You can also set multiple collection for landing types.