Patent issue, I invented a special water tank and applied for a patent, and then received a correction notice. I want to modify the original file beyond the scope of the original file.

If there is no mention of a drain pipe in the original instructions, your modification would be out of scope if you add a drain pipe. If it is a utility model patent, there is no choice but to resubmit or apply for another patent; if it is an invention patent, it can be modified after the invention patent is submitted for substantive examination or after receiving a notice of entry into substantive examination.

In addition, adding drawings will change the filing date and application number of the patent.