Q: how do i transfer apps from old phone to new phone

Follow the instructions here or here; using the first set of instructions then requires syncing the second device with the iTunes library containing the content.

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You use iTunes. See this support document about transferring content from old device to new one. Transfer content from an iPhone, iPad, or iPod touch to a new device - Apple Support

If you don't routinely sync your old iPhone with iTunes then see also Recover your iTunes library from your iPod or iOS device.

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