Trump has the power to do anything that people (especially Congress) does not push back against.
> 1. Do not obey in advance.
> Most of the power of authoritarianism is freely given. In times like these, individuals think ahead about what a more repressive government will want, and then offer themselves without being asked. A citizen who adapts in this way is teaching power what it can do.
Elections are run at the state level, so it's not like Trump can direct state agencies to stop counting mail-in ballots. That said, the fact that elections are run at the state level, and the fact that only a handful of swing states matter means it only takes a few pliant election officials to change the outcome of the election. eg. if Georgia's governor caved in 2020.
Trump asked Texas to redistrict that they were all for it.