There are many tools to allow you to manage WordPress. I have found that two tools are at the top of my list. MainWP (https://mainwp.com) and WPMuDev (https://wpmudev.com/)
Main WP is self-hosted and you install it onto a server you have access. Overall it can be Free and provides a lot of functionality. If you want more features (I would suggest this) You can purchase a LifeTime subscription. This is a great tool.
WPMUDev is a subscription per site or for a larger agency fee. They provide custom plugins that are amazing. WP SMUSH is one that you probably have heard of. I really enjoy this tool and the way it allows you to manage a site. It may be expensive but worth the purchase.
WordPress Management allows you to maintain a WordPress site or sites from this tool. Backup, Updates, Plugins, and more.