Many schools can apply for multiple majors. If an application fee is required for each major project, multiple applications need to be submitted.

However, there are some exceptions. For example, Imperial College London, London, made it clear that you can only apply for two projects at most, and make clear your preferences. After the first choice is rejected, the school will continue to consider the application of the second choice.

Generally similar information can be found on the admission page or FAQ page. I suggest you get in touch with the graduate admissions office or the target department before applying, and ask how many projects you can apply for at most.