Where to put each tagged link
In your Business Profile dashboard, replace the plain website link with the tagged version, and do the same for the appointment link if you use one. Google Posts each get the posts link. From then on, GA4 shows these visits under source "google", medium "organic", campaign "gbp-listing" (or your custom campaign), separated cleanly from ordinary search traffic.
One caution: tag the link fields only. Do not change your business name, categories or address to include tracking or keywords — that violates Google’s guidelines and risks suspension.