The Free Pascal compiler issues 32-bit or 64-bit code. This has several consequences:
You need a 32-bit or 64-bit processor to run the generated code.
You don’t need to bother with segment selectors. Memory can be addressed using a single 32-bit (on 32-bit processors) or 64-bit (on 64-bit processors with 64-bit addressing) pointer. The amount of memory is limited only by the available amount of (virtual) memory on your machine.
The structures you define are unlimited in size. Arrays can be as long as you want. You can request memory blocks from any size.