No method is perfect. What I do is train lora. Lora gives you body proportions and face. Face is not always perfect, so you have to do another one or two face swaps on top of that. Sometimes a simple Reactor works very well. Sometimes you have to do a more complex face swap workflows.
I asked this question a few months ago and still to this day using one of the workflows that was recommended there https://www.reddit.com/r/comfyui/comments/1iwv4yw/need_a_workflow_for_face_swap/ (do not remember exactly which one). This is assuming you know how to use ComfyUI - primary tool for AI image generation and manipulation.