Typically these platforms will query on a data warehouse that you provide: redshift, bigquery, a big postgres instance, or the like.
In terms of getting data into that warehouse, you can write ETL (extract, transform, load) scripts yourself. There are also a number of ETL-as-a-service providers like Stitch or Fivetran that cover common things you might want to sync into your data warehouse and query like salesforce, google analytics, quickbooks, etc: https://www.stitchdata.com/integrations/sources/
In terms of getting data into that warehouse, you can write ETL (extract, transform, load) scripts yourself. There are also a number of ETL-as-a-service providers like Stitch or Fivetran that cover common things you might want to sync into your data warehouse and query like salesforce, google analytics, quickbooks, etc: https://www.stitchdata.com/integrations/sources/