You can use this library https://marketplace.thingworx.com/Items/csv-parser in order to generate CSV files with the data you want to export.
Also you can generate easily JSON files and or XML
Don't use this extension https://marketplace.thingworx.com/Items/Data%20Export%20Extension as the Excel generated will be a pain to process ( almost all the data it's not generated on the correct Excel data format )
It will depend on how you want to ingest the exported data.
To query the data, if it are on ValueStreams, you will need to use Query"baseType"PropertyHistory to get the data, if it are Streams the corresponding QueryStream services.
On previous versions ( before 6.5 ) with exporter services you where able to generate XML/JSON files for Data, but not (at least from composer) it's not possible, it exports the data on propietary binary format that you will need to reverse-engineer.