Historically, frequent API calls prevent Tesla vehicles from sleeping, however since firmware 2023.11, API calls do not prevent recent vehicles from sleeping, except Model S and Model X vehicles manufactured before 2021 which have not had their MCU upgrade.
The custom Home Assistant integration (v1.9.3 and newer) will identify when your vehicle has been inactive (not charging, no user present, no sentry mode) for 15 minutes, then will stop polling updates for 15 minutes to try allow the vehicle to sleep. This process will repeat with 15 minutes on and 15 minutes off.
The only thing that will keep your vehicle away is running commands, so if you find your vehicle is not sleeping (see status entity), check that you do not have automation running commands.
Fleet Telemetry will not impact your vehicles sleep at all, in fact it is the most reliable way of determining if a vehicle is asleep or awake as it does not require constant polling.