The can protect you from three layers of mobile tracking.

The first is the tracking present in traditional operating systems that send unique identifiers from your phone, cell service, along with personal information to Google and Apple servers. The comes with your choice of two operating systems. GrapheneOS is focused on absolute security and does not include any Google apps or services, avoiding making any connections to Google servers.

CalyxOS comes with its own compatibility layer (microG) that greatly reduces the data sent to Google while retaining functionality with apps that depend on Google Libraries.

The second is the tracking present in traditional mobile applications through analytics and advertising services. The phone utilizes Free & Open Source Applications which contain no embedded trackers. Additionally the user has the freedom to download existing proprietary applications and control their connections.

Lastly, the protects you from cellular service tracking through several means. First you can use the phone on WiFi without a SIM card. This avoids any cellular connections but you will not be able to go mobile.

If you use a cellular service you can avoid making calls and texts (which are tracked by your provider) and use encrypted communications along with a VPN to protect your internet traffic. You can also use & XMPP to call and text over the internet.

You have the freedom to choose how to use the phone in every instance based on your own privacy / security needs.