I want to make sure I understand your question. Do you mean that you want to download an Adobe Stock image created by a different artist, add a post processing effect and message to it and then upload it to Adobe Stock to sell as your own image? If that is what you mean then the answer is a definitive no. You must own the copyright to all content you upload to Adobe Stock. Purchasing a license (standard or extended) does not provide you with the copyright. That remains with the original artist.
If however, your intent is to purchase an image with an Extended license and then sell the image featured on a product such as a coffee mug or a postcard then yes, that is allowed.
Please refer to the license agreement for specific details on allowable use.
Thank you,
Mat Hayward