Activate Features For Sites. Pretty straight forward and easy enough through the UI isnt it. On the Site Settings page under Site Actions click Manage site features.

Let web pnpspweb. See System Requirements for additional information. The following line is asking which features are enabled at the Web Scoped level.
Unless youre looking for Publishing Infrastructure Content Organizer and the Document ID Service activated across all sites in all web applications dont use the Enable Features on Existing Sites function within Central Administration.
However if you want to see if your feature is installed then you need to use Get-SPFeature without. SiteConn Connect-PnPOnline -Url SiteUrl -Credentials Cred. To activate a site collection feature from SharePoint web UI You can navigate to Site settings Site Collection Features Click on Activate next to the relevant feature. Subscriptions covering all devices are limited to supported devices that you own.