You really, really can’t put any of those other things next to a virus and have the scale be perceptible. The thing you are suggesting is a thing that would not work. A virus is something like a thousandth the size of an amoeba.
Much like they did in the 1962 version—they’ll just make Kong bigger, I think.
Toho didn’t bother to explain it, but this time they set the groundwork for that in Skull Island. Kong was 4 times larger there, and John C Reilly’s character said he’s still growing. They set that film, what, 50 years ago? So I think Kong will be all grown up by 2020.