You can choose to change the topic halfway. It is also common to change subjects halfway, so there will be less time for later subjects, so graduation is likely to be postponed.
There are many reasons for changing subjects halfway, which may be that students don't work hard, that the tutor has some deviations in choosing topics for students, that the tutor didn't give good guidance, or that the subject itself is the reason, that is, no one knows what the result will be, so they can only grope and try a little.
The opening report refers to the written explanation of the scientific research topic by the initiator, which is an applied style. It is one of the basis materials for the graduation thesis defense Committee to examine students' defense qualifications. The author outlined his topic selection to relevant experts and scholars. Then they will evaluate the scientific research project, and then the scientific research management department will comprehensively evaluate the opinions and decide whether to approve the project.