...just as Sodom and Gomorrah and the surrounding cities, which likewise indulged in sexual immorality and pursued unnatural desire, [literally, pursue different flesh] serve as an example by undergoing a punishment of eternal fire.
“Sexual immorality and perversion” suggests that the sin of Sodom was, at least in part, sexual i.e. the homosexuality that the story reports. The phrase literally means “to go after strange flesh” suggesting, not normal but, perverted sex.
Understanding Jude 7