When people have a wrong perception (i.e. that Biden did poorly on the economy) you cannot contradict them or lecture them. That's a losing strategy. But if you don't correct them they will continue to blame Biden. That also loses.
The border/immigration suffers from similar perception problems. When people believe that dems are shuttling illegals to swing states in order to steal the election, how can you respond to that? Or to claims about illegals eating cats and dogs? Trump is very effective at messaging that invokes strong emotions.
People will forget about grocery prices and the border once Trump is in office. Trump will shout things and maybe do a few publicity stunts and that's enough to appease people. The actual reality matters little.
Lowering govt spending PLUS raising taxes would have been the way.
"Reducing prices" means deflation, which doesn't happen outside of a depression. Triggering a depression intentionally is absolutely bonkers in terms of policy.