It can be time-consuming to manually share new posts to each social media account. Not only that, it is also sometimes difficult to find the right plugin for the job. After doing some research and testing out different plugins, I have found that the best WordPress plugin to auto share posts to social media is Jetpack.
Jetpack has many features that can be beneficial to your website. The plugin is free but you can always upgrade it for more.
Install the plugin
To install the plugin, first click “Add new” under “Plugins”.

Search for “Jetpack” and click “Install Now” on the first result and “Activate”.

Once activated, you will be taken to the setup page. Click the “Set up Jetpack” button.
You will be taken to WordPress.com and be asked to create an account. Create an account if you do not already have one. Otherwise, sign-in to your existing account.
Once signed in, scroll to the bottom and click the “Start with free” button.
Enable auto-posts
Navigate back to your website’s WordPress admin and click on “Settings” under “Jetpack” located in the left-hand navigation.

Click “Sharing” in the top bar.

In the first box, switch “Automatically share your posts to social networks” to on.

Connect social media accounts
Once turned on, click “Connect your social media accounts” in that same box. You will be taken back to WordPress.com. From there, click “Connect” and go through the steps for each social media account that you would like to post on.

From there, all new posts will automatically be published to your social media accounts.
Conclusion
To sum up, the best WordPress plugin to auto share new posts to social media is Jetpack. All you need to do is install the plugin, create an account, turn on auto posts and connect your social media accounts.
If you know of a better plugin, please let me know in the comments down below!