Symplify checks your website for GA4 implementations. It will automatically check if you use GTAG or GTM to implement GA4.
By default, Symplify is set to send events to the Google Analytics Measuring ID(s) implemented on your website. These events contain project and variation information and can be used as segments in GA. This way you can check all your KPIs in GA for a specific project by comparing the project variations. However, we do recommend using the Symplify statistics for evaluation of the project and only use GA for other KPIs than conversion rate and/or project success.
GTAG
If GTAG is used to implement GA4 on the website the Symplify script will push the Symplify events automatically to all Measurement IDs on the website. This happens only the first time a visitor fulfils an Audience (per project).
GTM
If GTM is used the Symplify events are pushed to the data layer. This happens only the first time a visitor fulfils an Audience (per project). You will need to set up GTM to fetch this event and pass it through to GA4.