Yes, the store owner can give the warning to their shoppers to upload the high-resolution image and can even configure the minimum and maximum size for the custom image upload.
Backend
Go to > Stores > Configurations > Product Designer Settings > Custom Image Upload.
> Choose “Yes” for showing the instructions while uploading a customized image.
> Type the instructions that will be displayed while uploading a customized image.
> Enter the Minimum and Maximum Size for the Image in MB (Megabyte).
This kind of warning will be shown to your customer while uploading the custom image.
