There are two ways to restore your iPhone from iCloud.
1, Restore the entire iCloud backup.
If you erase all the iPhone data, or you have a new iPhone and need to restore the whole backup from iCloud, you canand all the data in iCloud backup will be back on your iPhone.
2, Selectively restore iCloud backup.
If you need only some part of data in your iCloud and wanna keep the current data on your iPhone, you can use one excellent iPhone data extractor to restore your data in iCloud backup.
I think, or , is what you exactly need.
iMyfone D-Back can detect 20+ frequently-used data in your iCloud backup and extract them onto your computer.
You can preview the particular content of iCloud backup so that you confirm which ones are you need before extraction.