Can I access more data with a Legacy Account upgrade?

Hi, my sister has access to my father's data due to a legacy account set up before his death. This is for 5GB of data which was at full capacity. If we pay for additional storage will we get access to the additional data (above 5GB)? This would include downloads that he made which would be helpful to access. Also if we do subscribe are we able to cancel at anytime? thanks

[Re-Titled by Moderator]