Can someone access my iPhone from another device?
Check if a device is linked
[Re-Titled by Moderator]
AirTag
Check if a device is linked
[Re-Titled by Moderator]
AirTag
No link is possible if you have not shared your Apple ID with others and have not Jailbroken.

One:
On your iPhone, go to Settings > Messages > Text Message Forwarding. If you can't see Text Message Forwarding, go to Settings > Messages. Turn off iMessage, then turn it back on. Tap Send & Receive, tap Use Your Apple ID for iMessage, then sign in with the same Apple ID used on your other devices.17 Nov 2023
Forward SMS/MMS text messages from your iPhone to your ...

Two:
Do any of the following: Tap Calls on Other Devices, turn on Allow Calls on Other Devices, then choose the devices on which you'd like to make and receive calls. This allows other devices where you're signed in with the same Apple ID to make and receive calls when they're near your iPhone and connected to Wi-Fi.
No link is possible if you have not shared your Apple ID with others and have not Jailbroken.

One:
On your iPhone, go to Settings > Messages > Text Message Forwarding. If you can't see Text Message Forwarding, go to Settings > Messages. Turn off iMessage, then turn it back on. Tap Send & Receive, tap Use Your Apple ID for iMessage, then sign in with the same Apple ID used on your other devices.17 Nov 2023
Forward SMS/MMS text messages from your iPhone to your ...

Two:
Do any of the following: Tap Calls on Other Devices, turn on Allow Calls on Other Devices, then choose the devices on which you'd like to make and receive calls. This allows other devices where you're signed in with the same Apple ID to make and receive calls when they're near your iPhone and connected to Wi-Fi.
Can someone access my iPhone from another device?