By default, the library will load when the first gtag action is called. This means a page will not load the gtag.js library if no page view, event, or set actions calls are made. This reduces the amount of assets your end users will have to load.
If you want to force the gtag.js library to load on every page, no matter if any gtag actions are called, or you want to load the gtag.js library earlier on the page, use this action to do so. It will only load the gtag.js library and configure the accounts setup in the extension configuration. If the gtag.js library has already loaded, it will not be loaded again.