What is the ruling on working in the field of preparing research papers and assignments and selling them to students, and is the money earned from that permissible?

Preparing research papers for students and submitting them as if they were their own work and effort is considered forbidden cheating and forgery, and cooperation in sin and falsehood, as Allah says: "And cooperate in righteousness and piety, but do not cooperate in sin and aggression," and the Prophet (peace be upon him) said: "Whoever cheats is not one of us." As for helping students learn how to write, format, and draft research papers, there is no harm in it, and it is permissible to take a fee for it.