Downloading DLC files from unauthorized sources (torrents, file-hosting sites like Mega or MediaFire) constitutes copyright infringement. Bethesda Softworks retains strict ownership of the assets.
Some "downloadable content" is now integrated into the base game through the Creation Club (e.g., Enclave Remnants), which downloads automatically upon launching the game and logging into a Bethesda.net account. Important Security Warning Fallout 4 Dlc Files Download
DLC files depends on your platform and whether you are installing them normally or moving files between versions (like for VR support). Official Download and Installation Fallout 4 Dlc Files Download