Are you talking about Salesforce Models? If so, the Maximum number of records that a Model can retrieve is limited by the "Heap Size" limit in Salesforce. Functionally this can be totally different depending on the number of fields in your Model and how much data is in each field. For example, for a Model on the Account object selecting just the Name, Type, and Id fields, you can likely retrieve 1000's of Accounts before hitting the heap size limit, but if you're retrieving 100 fields on the Case object, including some Long Text Fields like "Description" with lots and lots of data in them, you might only be able to retrieve 500 Cases before hitting the heap size limit. These numbers are all just chainsaw-math of course, but the point is that "it depends" on the number of fields in your Model and what data is in those fields.