you can test this yourself by copying a single file to the remote
for example, something like rclone copy file.ext remote: -vv
in the debug output, would see something like
DEBUG : file.ext: Need to transfer - File not found at Destination
DEBUG : file.ext: md5 = d41d8cd98f00b204e9800998ecf8427e OK
INFO : file.ext: Copied (new)
Is there any way to know in advance if it does so with the storage system I'm transferring to?
I'm performing an rclone transfer from an ext4 partition to "OneDrive For Business", which has had shaky support in the past due to it differing from OneDrive.