How to get iOS 13?

We are other end users, not Apple.. We cannot "give" you any iOS version.

You've not said what device this is for. Older iPhone and iPad models cannot run higher than iOS 12.X.

If your device is not listed here, you cannot use iOS 13:

If your device IS eligible, Settings > General > Software Update will show iOS 13 as available. If not, you need a newer phone or iPad.

ruhe48 wrote:

not question just I need ios 13

The only way to do this is by purchasing a used device that already has iOS 13 on it.

Unfortunately, you must find a device that already has iOS 13 installed. In some cases, you can buy an older device that cannot be upgraded past a certain version. Those devices would be guaranteed to run that last version. But according to this chart, there is no device that is maxed out at iOS 13.