Try the resize button - https://www.canva.com/pro/magic-resize/
Learning what content your audience is engaging with will allow you to assess the success of your Pins. This data can help inform the content you create and publish. You can also leverage audiences from other platforms, directing them to Pinterest to engage with your content and build your following.
Discover Pinterest’s best practices
Find out how you can claim from other platforms to cross-promote content and widen your reach
Learn how to easily resize your designs with Canva Pro to promote your Pins across channels
Pinterest Templates and Design School Resources -
https://canva.me/pinterest-templates
https://canva.me/design-school-pinterest