Hi @PatrickMast, apologies for the delay here!
We don't have a config setting for this on the file uploaders, but you should be able to handle the parsing in a JS query with more custom settings.
For example, we use Papa.parse in Retool already, and there is a preview property that can limit the number of rows parsed for CSVs, etc:
We also have utility for excel files, which uses Sheets JS + accepts a Sheet range:
