Is it permissible to enter a chat room with a female username for the purpose of guiding and directing young men, given that entering with a male username does not achieve this purpose?

Inviting people to Allah is fundamentally based on truthfulness in all its forms. Assuming another identity is a lie and a deception, especially given its ramifications, such as speaking in the feminine form. Lying is not necessary to guide people, for hearts are in the hand of Allah, and He is capable of guiding them. Adhere to truthfulness for the blessing of your words and the guidance of hearts, for the Prophet, peace and blessings be upon him, said: "Indeed, truthfulness leads to righteousness, and righteousness leads to Paradise."