Most funding agencies, publishers, or other research supporters, require a data management plan. The idea being that if they fund your research, the data resulting from that research must be Findable, Accessible, Interoperable and Re-useable (FAIR).
You may wish to create a data management plan even if there is no funding requirement because it will help organize your data. Having a data management plan in place when working in a team is really important, so that everyone on the team is aligned about file formats, naming, and storage, and sharing. Taking some time to think about these things and write them down before the project begins will help your project in the long run.