Can ShortPixel automatically resize new image uploads?
Yes, ShortPixel allows you to resize the images when uploading them. This means that you can upload an image of any size; ShortPixel will take care of resizing it.
You can find the setting going to ShortPixel > Settings > General > Resize large images:
Please note that the feature resizes only the full original images, not the thumbnails. You can find more details about it here.
The resizing option works also when Bulk ShortPixel is run on existing images.
Also, take into account that, even though it's uncommon, your hosting might limit the size of your uploads. Therefore, if you can't upload a big image, it will be better to check it with your hosting, as ShortPixel accepts any image size.