What level does the assistant general manager of the property belong to?

This depends on the internal settings of the enterprise.

If it is defined as an assistant to the general manager in business work, who can complete a job independently, then this assistant is equivalent to the level of department manager or property project manager in all departments of the property company.

If you just assist the general manager in his daily work, handle some documents and arrange the work schedule. This kind of assistant is equivalent to the secretary of the general manager, and the administrative level is at most the supervisor level. But the salary may be higher, equal to that of the department manager.