After the patent application is submitted, can the applicant take the initiative to propose amendments?

You can take the initiative to modify it within two months after submission; The invention patent shall be amended by itself within 3 months after submitting the application for real trial and receiving the notice of real trial;

However, active modification is not how to change it as you want, and the modification can't go beyond the scope recorded in the original manual anyway; It is impossible to add "what cannot be clearly drawn from the original specification" to the specification. If you want to add such content, you can only apply for a new one with the priority of the previous patent.