Here is my solution, but I couldn’t fix some problems.
For skeletal meshes that are only visible in the first person, the default settings should be: visible = false, only owner see = false. When creating character change the visible to true for these skeletal meshes(image 1)
When you move into spectator, you need to pass it a link to the killer or any other character. And after in it already when choosing first person make skeletal mesh visible, but only for this spectator(image2)
But I have a problem. When I possessed to character and switch mode to first person, I can’t observe the pitch camera changes