Does quality increase with file size increase?

For example, raw footage from my P4P is .mov shot in H264 4K@30FPS totalling 5GB. If I transcode it to a ProRes 422 it increases the file size quite significantly. Does this increase the quality or just the file size? If it's just the file size, what is the point of using a file format that just increases the size of a file?

Does quality increase with file size increase?

For example, raw footage from my P4P is .mov shot in H264 4K@30FPS totalling 5GB. If I transcode it to a ProRes 422 it increases the file size quite significantly. Does this increase the quality or just the file size? If it's just the file size, what is the point of using a file format that just increases the size of a file?