You don't NEED ESPN+ to get the games.
ESPN+ is a service you can buy without a TV subscription, cable or streaming. It offers access to SOME live sports, but also their premium content and articles on their website and some reserved content and backlog catalog of things on the ESPN+ app.
If you have SECN through a TV provider, then the VAST VAST VAST majority of those have the ability to use your account to authorize SECN+ in the ESPN app. You'll often see 2 versions of a game, one showing ESPN+ and one SECN+, so just know you'll need an ESPN+ subscription for those labeled ESPN+ and a supported TV provider (like YTTV) to watch the ones labeled SECN+.