Short answers, pulled from the story.
Capcom began building the RE Engine in 2014 during the early development of Resident Evil 7: Biohazard. The team abandoned their previous MT Framework system and Panta Rhei engine to improve production speed.
Capcom requested that Nintendo increase the console's onboard RAM from 2GB to 4GB capacity before development began. This upgrade was necessary to make the Switch potent enough for developing games using the RE Engine without severe memory constraints.
Resident Evil 7: Biohazard launched in 2017 as the first title built with the new engine. It appeared on PlayStation 4, Windows, Xbox One, and later ports to other platforms.
Jun Takeuchi led Division 1 and stated they had to rethink how games were made when starting the project. He explained that asset-based development was becoming the global standard for graphics and 3D models.
Capcom unveiled Codename REX during a developer-focused presentation in October 2023. The event outlined plans to incrementally integrate RE+X technology into the existing framework.