New information on long term deep space radiation exposure, new information on long term space travel in general. Lunar research not done before, now possible due to lunar research station. The list goes on and on. You can look up all research projects included in the Artemis missions online

the van allen probes give us higher quality and longer term data about radiation.

we are pretty aware of regolith constitution.

having a moon base (which isnt in artemis 3) is not research