Hi seydina128,
The Find My network is end-to-end encrypted. This means that Apple and other third parties cannot access the location of your Mac or iPhone through Find My; only you can.
If your iPhone and Mac are offline, that doesn't necessarily mean that they are lost forever. If both devices are powered on (asleep/locked is ok) and have Bluetooth enabled, by default they will search for other nearby Apple devices. If other Apple devices are found, and those devices have an Internet connection, your Mac and iPhone will instruct those devices to relay their current location to you so that you can find your devices.
If you have the serial numbers of your iPhone and Mac available, you should report your stolen devices to law enforcement. Include the serial numbers in the police report.