You can easily upload your GIF files of 10MB or smaller to a GIF Post type:
(If you have a link to the GIF, you can choose the Website Link Post type, just know that guests might have to click on that GIF link to view it. So try the GIF Post type first.)
If your GIF won’t upload and you’ve created it yourself on a program like Canva, it might be too big.
You can try these tips to resize your GIF file:
You can edit your GIF from the program you created it in, by removing some graphics or choosing smaller ones or choose a lower quality/resolution when downloading.
You can try uploading it to www.giphy.com and immediately download it again because giphy automatically resizes their gifs.