(You can access this feature if you have a Canva for Work account)
With Canva for Work, you can easily change your design’s dimensions and rotate it from portrait to landscape and vice versa. Steps are indicated below.
01. Click File
On the editor page, click on File found on the upper lefthand of your design page.
02. Use Custom dimensions
Click on Change Dimensions > Use Custom Dimensions then enter your preferred dimension.
Alternatively, you can choose from the list of templates available.
Note: For Standard (Free) Canva accounts, you can create a landscape design by using the Custom Dimension feature (with measurements of 36 x 24 in) before you start designing.
Thanks for your message, I'd be glad to show you how to create or change a design to a landscape format!
After a design is created in a Canva standard (free) account, you cannot change the dimensions of the design. If you want a design with landscape-style dimensions, you need to create it with those dimensions from the beginning.
To create a design in landscape orientation, create a design with custom size dimensions. Please ensure the width of your design is greater than its height!
On the other hand, you can directly change your design to a landscape format with a Canva for Work subscription. You have the option to change the size of your design even after the design is done! Just click File, Change dimensions, then choose Use custom dimensions and finally, enter the desired dimensions. At this time, you can only resize designs in the pixels unit. Thus, I can recommend you use this tool for unit conversion.
More information can be found here:
How do I change my design to a landscape format?
I hope this helps, please do let me know if you have any further enquiries!