If you were using a filesystem that supports multiple partitions, then sure, you could do that.

I remember that being a big deal with Digital AdvFS, a long time ago, on architectures now far, far away... <https://en.wikipedia.org/wiki/AdvFS>

Filesystems you could actually choose that support adding multiple block devices to a filesystem include BTRFS (I have used the facility) and probably ZFS.

Unfortunately, if you make your filesystem dependent on multiple drives all functioning properly, you have accepted a pretty big dollop of risk, so I'd be inclined, myself, to copy material over to the new, larger drive.  (The problem is, and I did run into this, that if ANY drive fails, there's a fair chance you wind up losing the entirety of the filesystem.)  But if your appetite for risk is higher, that may be  acceptable.  (I accepted the risk, at the time.)