To add hashtag support to the Publicize feature, download the Publicize with Hashtags plugin from WordPress.org, or visit the plugins section of your WordPress dashboard and install and activate the plugin from there.
Publicize with Hashtags allows you to automatically append hashtags when you share your content through the Jetpack Publicize feature with the use of post tags. for instance, if you’re writing a roundup of a recently attended conference, you can tag the post with the conference’s hashtag, (excluding the # sign), and your tag will be automatically appended to what the Publicize feature posts, without exceeding the 118-character limit of the social message text.
Jetpack’s Publicize feature is far from the only way you can share content to social media using WordPress. But if you’re using Jetpack, and you have this feature activated, appending hashtags that are taken from your post’s tags is an excellent way to increase the reach of the content you’re creating. I hope you find this as helpful as I have.