Here is the section of the model 3 manual related to the alarm in the version of the manual that is found when you search "tesla model 3 manual" online. Note, the page numbers might be different in the version of the manual you have. Alarm states are covered in the manual pretty extensively, but on page 143 in the manual I just referenced above you can find this section (bold emphasis mine):
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About the Security System
If Model 3 does not detect an authenticated phone, key fob, or key card and a locked door or trunk is opened, an alarm sounds and the headlights and turn signals flash.
To deactivate the alarm, press any button on the mobile app or tap your key card or key fob against the card reader located just below the Autopilot camera on the driver's side door pillar.
To manually enable or disable the alarm system, touch Controls > Safety & Security > Security Alarm. When enabled, Model 3 activates its alarm one minute after you exit, the doors lock, and a recognized key is no longer detected.
If your Model 3 is equipped with the security package, a battery-backed siren sounds in situations where a locked door or trunk is opened and Model 3 does not detect a key nearby.
If you also want this siren to sound in situations where Model 3 detects motion inside the cabin, or is moved or tilted (for example, with a tow truck or jack), turn on the Tilt/Intrusion setting (Controls > Safety & Security > Tilt/Intrusion).
NOTE: If you plan to leave something that moves inside your locked Model 3, remember to turn off Tilt/ Intrusion (if equipped). If this setting is on, any motion detected inside Model 3 activates the intrusion alarm.
NOTE: Note: If Model 3 is in Sentry Mode (see Sentry Mode on page 141), you must disable Sentry Mode before you can disable the Security alarm or the Tilt/ Intrusion alarm.
NOTE: The Security Alarm must be on to enable Tilt/ Intrusion. NOTE: The Intrusion Sensor automatically disables in situations where the climate control system is operating when you have left your vehicle (see Keep Climate On, Dog Mode, and Camp Mode on page 127). To override, you can manually turn the Intrusion Sensor on again after choosing Keep Climate On, Dog, or Camp Mode (touch Controls > Safety & Security > Tilt/Intrusion).