In the stereotypical ezcap boards you can test this by connecting an appropriately long wire antenna to the right side of capacitor 17 on EzTV 1. IF gain can be set through the API.

Make sure to start multimon reading the fifo before you begin GRC and execute the receiver. I also remove the superfluous throttle block. Version 22b is a bit version based on Ubuntu

This requires passing an initial ppm error parameter from LTE scanner -e. If you're using GNU Radio 3. It has updated software packages, a fresh kernel, and a higher gain VGA setting in the rtl-sdr firmware.