@nprofile1q... do you mean in fiction or in relation to alleged 'Close Encounters of the Third Kind' that real people believe they've had ?
The answer IMHO that same for both, UFI stories are not actually about UFO's but are really about some contemporary threat and / or cultural fear / anxiety.
*Big* is more of a threat than small / micro unless the central point of the story / propaganda is that small thing is HIGHLY DANGEROUS BECAUSE SO SMOL.