I have a new iphone 15. There is no way to connect to ear phones. What do I need to connect?

You can listen to podcasts using any of those choices.

I don't know what ear buds you currently have and whether you want to continue to use them. If you have existing earbuds that you like and if they have the 3.5mm connector and you want to continue to use them, then an adapter is the only option: Lightning to 3.5 mm Headphone Jack Adapter - Apple

If you don't care about using your existing 3.5mm earbuds (or if they are the old earbuds from Apple that came with a previous phone) and you want an inexpensive wired earbud like those that used to come with iPhones, then a good choice would be the following and no adapter is needed: Lightning to 3.5 mm Headphone Jack Adapter - Apple

If you want something that connects wirelessly and want to spend some money then AirPods - Apple

One option: Lightning to 3.5 mm Headphone Jack Adapter - Apple

Another option: EarPods with Lightning Connector - Apple

Other options: AirPods - Apple

There is no such thing as an iPhone 15.