Family plan parameters
Parameters of accessing my iPhone data (tracking, texts, etc) if I am part of a family plan but not the actual subscriber.
iPhone SE, iOS 15
I am pretty much completely failing to understand what you are asking. There is no subscription for Family Sharing. It is an agreement between the Organizer who sets it up and the people the person invites to be part of the family group
Texts have nothing to do with Family Sharing.
Tracking? There isn't really any tracking as such. Do you mean Screen Time? --> Use Screen Time on your iPhone, iPad, or iPod touch - Apple Support or Find My? --> Turn off Find My on your iPhone, iPad, or iPod touch - Apple Support
There's various parental controls but those aren't tracking as such:
Set up parental controls with Family Sharing on iPhone - Apple Support