During the period of bail pending trial, the suspect can write his own surrender materials and hand them over to the police, right? Does this mean that confession is lenient?

Since a friend has been released on bail pending trial, I won't sue your friend. At most, he will be directly released on bail pending trial and prosecution, telling your friends to actively cooperate with the public security organs, and a good attitude determines everything. You can write it yourself. Don't blindly admit mistakes in your writing. You should expose clues that other public security organs don't have. As long as you have meritorious service, you can reduce or exempt from criminal punishment.