can you purchasea longer tingtone

Here is an example of the ring options available from AT&T:

Go to Account overview > My digital phone > Check or manage voicemail & features. On the Voicemail Settings tab, scroll to General Preferences and select Set Number Of Rings Before Voicemail. Choose a setting ranging from 1 ring (6 seconds) to 6 rings (36 seconds). Select Save.

Change Number of Rings Before Voicemail Answers - AT&T

There is no additional charge for these options.

If you are using a different carrier, check with the support folks there to see if they have a similar option for their service.

Changing your ringtone will not change the length of time your phone rings, this is determined by how long the person calling you chooses to wait before ending the call.

Regardless, if you still wish to change your ringtone, go into the settings app > Sounds and Haptics > Ringtone > and then pick the ringtone you want.

If you wish to purchase a ringtone other than the standard ones, click 'Tone Store'. You may then be prompted to download the iTunes store if it isn't already downloaded on your device. Once on the iTunes store, you can purchase a ringtone of your choosing.

Can you get a long ringtone?

All ringtones are max 30 seconds.

That's awesome that AT&T is making that user-selectable. I hope it's something other carriers do. For years, you've had to call the carrier.