When querying endpoints like /history or /txs, it is unlikely that you'll get all the transactions needed in one page.

When there are more results to process, the output will include a nextPageUrl field. There's also a boolean field called hasNextPage which will tell you whether you should be fetching another page of results or not.

To go through pages, simply get the URL from nextPageUrl in each call, and call that URL for your next page until you're done.

For an example of how to do this, check out this section of a related guide.