Those who have installed mods for GTA 5 may have used a tool named Script Hook V for the same at some point.

You can mod GTA 5 in two ways: With .ASI mods and with .DLL mods. Either way, you'll need to install some other add-ons like Script Hook first.

Once the script is loaded you can use a few keyboard commands to enable the grappling hook and start attaching people to objects, objects to people and everything else in between.