In order to change the logging level for xConnect you need to update the following file in you xConnect instance:

\App_data\Config\sitecore\CoreServices\sc.Serilog.xml

The default level can be changed by updating the value here:

image001-1

Here's a quick reference on possible values [1]:

image002

  1. https://github.com/serilog/serilog/wiki/Configuration-Basics ↩ī¸Ž