Hi Sam,
Thanks for reaching out to the Adobe Stock community.
The size or dimension of the files are mentioned below each image as shown in the screenshot:

Additionally, all Adobe Stock content is provided at its highest available resolution. While this resolution depends on the camera used to originally capture the asset, most of the content can accommodate high-quality printed output up to 300 dpi.
Also, the vector files can be printed in all formats without loss in quality. You may also refer to Common Questions, Adobe Stock for more details.
However, I would like to let you know that since you are using these assets for splashback, you will be requiring an Extended license for the assets since under extended license asset may be featured in merchandise or products for resale.
For more information on the licensing terms and restrictions please refer to Stock Licensing & terms FAQ: Where can I find the terms and licensing information for Adobe Stock?
Hope this information helps!
Feel free to update this thread in case of any additional questions.
Regards,
Twarita