Objective: post your article and be able to show the final result of your article as a gif on the LinkedIn post.
The first step is to add a featured image which is a gif that you want to display when you post on LinkedIn, we do this by selecting three-dot from the left side of the medium and selecting the featured Image choosing the gif you post to show the final result.
Note: My Internet speed is slow so I have to wait for a couple of minutes for the featured gif to load.
The next step is to publish so we can see our feature gif is selected, if we see is selected in the preview before publishing now we can add tags to more of our medium discovered by some who are interested in game development staff, so use tags like unity3d, game development the hit publish now button.
The next step is to share the medium article post, but if you copy your URL and paste it on LinkedIn your post will show a static image and not the gif you intended.
To solve this make sure you click a shared icon for LinkedIn, this will pop up the window tab for LinkedIn with the gif played.
Last write the message about what is your article about, add the tag starting with a hash sign then post your article.
I hope It helps, take care