If you own the game but want to bypass Steam for offline archival, tools like Goldberg Emulator or SmartSteamEmu can be used with your legitimate files. This is a grey area but legal for personal backup purposes in many jurisdictions (per EUCD and US DMCA exemptions for abandoned software—Resident Evil 2 is not abandoned).
If your goal is to play Resident Evil 2 with all DLC and the December 2019 update (or newer), here are legitimate methods: residentevil2updatev20191218incldlccodex new
Let's break it down piece by piece:
In short, the keyword is a pirate scene label for an unauthorized December 2019 patch that adds downloadable content to a cracked copy of Resident Evil 2. If you own the game but want to