Backups store state at the point of backup.
Are you trying to implement a data retention policy that removes older data? If so, you'd need to implement processes to do that using periodic deletes, or possibly using table paritions (e.g., partitioned by year), which would allow you to truncate partitions that contain older data -- more sophisticated, more efficient for removing old data, but more complex to implement, & having potential impacts to query performance... Partitioning can be time-consuming on a large table. If you tried this, it might be best to start after existing old data was already deleted.
You'd probably want to use scheduled SQL Server Agent jobs to run the processes in either case. And consider archiving old data to different tables and different filegroup or database if you periodically need to use data older than two years.