Anyone who has subscribed to Microsoft 365 also gets 1 TB of storage space in Microsoft OneDrive. Via the standalone OneDrive app (App Store-Link) for iPhone and iPad you can access all your cloud data and from now on also upload RAW and ProRAW photos in the original format in the highest quality.
Since RAW photos are particularly large, you should make sure that you still have enough storage space. A ProRAW photo from the iPhone camera is on average at least 50 MB in size, often larger.
Another thing I should note is that the OneDrive app for iOS will soon end support for iOS 14. You must have at least iOS 15 or iPadOS 15 installed to use the OneDrive app. However, Microsoft does not announce an exact timetable here.
Microsoft OneDrive is free in the Basic tariff and offers 5 GB of cloud storage. The OneDrive standalone tariff costs 20 euros a year and offers 100 GB of storage space. 1 TB of storage is only available in connection with a Microsoft 365 subscription. There is an overview here.