From release notes:
Oodle Texture compression are the fastest and highest-quality encoders for block-compressed BC1-BC7 textures. Oodle Texture’s Rate Distortion Optimization (RDO) encoders can make high visual quality encodings that are 2 to 3 times smaller than the non-RDO encoders!
Oodle Texture compression is enabled by default in Unreal Engine and RDO encoding can be enabled in the Project Settings (RDO encoding is off by default).