Yes, by default with csv as sourcetype for window event logs - it will extract _time, date and time, event_id, extracted_source, level, task category and the EXTRA_FIELDS_6 - if you still need the EXTRA_FIELD_6 to be parsed and properly extract the fields you need to field-extraction using regex (OR) delimiters.
try this link, you ll have some idea,
https://answers.splunk.com/answers/145841/is-there-any-way-to-manually-load-a-windows-event-log-into-splunk.html
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