Speaking of which, do you know if it’s possible to start and end recording in slow motion immediately instead of it starting and ending at normal speed with tra

Speaking of which, do you know if it’s possible to start and end recording in slow motion immediately instead of it starting and ending at normal speed with transition between? Also when I transferred videos from my iPhone to my computer and watched the videos in VLC they played back at normal speed so I guess the slow down is actually recorded as meta-data either inside the video or someplace else in iOS so that it is non-destructive. In turn of course that means that I can watch the whole thing on the computer at any speed I desire but when I talked about the normal speed stuff I mean when I watch it on the phone itself.