I do not like the name of the app OneDrive integration. It is not an integration, it is only an import of Microsoft OneDrive files in Nextcloud.
First the best thing is to use a bigger internal storage of your Nextcloud. Where do you host your Nextcloud? Post details of your Nextcloud. Maybe we can help you.
Also you can use not one but two or more different Nextclouds. You can manage them in one Nextcloud app and also you can use e.g. federation (docs). I use a lot of different Nextclouds. I have distributed the data in such a way that I rather do not have to exchange data between the Nextclouds. E.g. photos only on one of the Nextclouds. Normal data on another Nextcloud.
The third possibility (but already far worse) is to use External Storage. And yes you can use Amazon S3.