None of the iPhone 12 models include a 3.5mm headphone jack. Apple eliminated the audio port from its flagship iPhone models with the release of the iPhone 6s. The iPhone SE was the last model to have a headphone jack before it was discontinued in March, 2020 with the release of the second-generation device.
iPhone users can connect wired headphones/earpods by using a Lightning to 3.5 mm headphone jack adapter. Otherwise wireless Bluetooth connected devices are required to listen to audio on all current iPhone models.