The operative adjective in 1 Cor 6:9 is μαλακός (malakos) which means: "soft".
It occurs four times in the NT as is usually applied to soft clothing such as was worn by wealthy people (as opposed to the cheap rough cloth worn by the poor), see Matt 11:8 (twice) and Luke 7:25.
In 1 Cor 6:9, BDAG offers this meaning:
pertaining to being passive in a same-sex relationship, effeminate,
especially of catamites of men and boys who are sodomized by other
males in such a relationship [See also Thayer and Strong's lexicons]
Thus, various versions translate the word as:
- male prostitutes (ie compliant in a male-male sex act), NLT
- men who submit to homosexuality, BSB
- homosexuals, NKJV
- effeminate (ie, in sense of being compliant in the male-male sex act), KJV, BLB, LSB, etc
Such a meaning appears to be a direct allusion to one of the forms of homosexuality that was common in Roman times and was a direct transgression of the instructions in the Torah such as:
- Lev 18:22 - You must not lie with a man as with a woman; that is an abomination.
- Lev 20:13 - If a man lies with a man as with a woman, they have both committed an abomination. They must surely be put to death; their blood is upon them.
- the condemnation of the Sodomites concerning the incident recorded in Gen 19