How would we create a devastating biological weapon in the open and use it on the population?

If we were seeking to take a very harmless virus that causes self-limiting infection or diseases (so it is non-noxious) and to then convert it (transform it) into a devastating biological weapon that could inflict mass casualties and destruction, then the approach would be simple and would be similar to the approach being used today in the US and other nations: we would continue mass population vaccination with a sub-optimal ‘leaky’ vaccine and suboptimal population-level immune pressure while within an ongoing pandemic with pathogen all around circulating, exerting tremendous infectious pressure, as is the case now. We would do exactly what we are doing now and just continue it. The virus will eventually escape from vaccine-mediated immunity targeting the receptor binding domain (RBD) on the spike! It is doing that now. An will continue to and we will never ever be able to achieve herd immunity or get out of the pandemic with these vaccines. We are set now for a lifetime of boosters ever 4 months or so. You just do not realize it yet. Likely, this was the plan day 1. This is about power, forced compliance, and money...criminality in my opinion. POTUS Trump was devastatingly mislead.