 So you want the cheat codes to professional character rigging, not a problem. The fastest way to properly weight paint a new character is actually with an old one. For example, if your character has similar proportions to the Unreal mannequin, you can straight up just transfer the weights by clicking it, shift click the new character, go to skin, copy skin weights, use these settings, apply, and you're done. All of the weight paint data from the old character is now automatically applied to your new one. In the mirror, you just export to Unreal and within 30 seconds, as long as your skeleton is identical to the mannequin, you can just swap it out and play your game. All that helps and as always, I hope you have a fantastic day and I'll see you around.