Given the current state of biotech, it is not possible to just edit the viral RNA achieving the desired clinical result, but is entirely feasible to keep applying minor edits and measuring the propagation rate in different tissues in vitro, effectively optimizing it to be more transmissible and less lethal. The snapshot of the phylogenetic tree, showing how Omicron "branched out" mid-2020 highly supports this assumption.
It is also quite obvious that an endeavor like this would be against all written rules and norms and would face backlash of epic proportion even if it wouldn't backfire, so it's safe to assume we won't hear an official confirmation of this theory from any of the governments.
[0] https://www.the-scientist.com/news-opinion/omicron-propagate...