Posting original size image instead of image thumbnail

Hi,

When I add an image to my post, I add it as the thumbnail size (350×350 for me). When I post to twitter, I want it to post the image as the original size (600×600) instead of the thumbnail size used in the post. Is there any way to grab the original size image and post that to twitter instead?

Thanks!

https://www.ads-software.com/plugins/twitter-auto-publish/