Trump and RFK Jr. looked at the Danish policy of fewer mandated vaccines at birth and copied that one single feature from a larger broader public health scheme.
What the Danes do is much better follow up post natal care for all newborn babies.
There's treatment at the first sign of (say) hepatitis B in Denmark, put in place early enough to avoid any severe liver disease.
The US would be better off, across all newborns, with a mandatory hep-B vaccine as a great many US newborns have no follow up post natal care to catch those cases that will result in liver damage for life.
If the US wants the Danish outcomes and reduced use of vaccines then the US also needs much better broader accessible affordable and effective post natal care.