On an iPhone, you cannot directly check the device's internal temperature through a built-in feature or setting. Apple does not provide a native temperature monitoring tool or an official method for users to check the internal temperature of an iPhone.
However, you can monitor the temperature indirectly by using third-party applications available on the App Store. These apps utilize the iPhone's various sensors to provide an estimation of the device's temperature.
To find temperature monitoring apps, open the App Store on your iPhone and search for terms like "temperature monitor" or "hardware monitor." Read the descriptions, reviews, and ratings of the apps to choose a reliable and well-regarded option. Keep in mind that these third-party apps may have varying degrees of accuracy, and it's essential to select one from a reputable developer.
Please note that using third-party temperature monitoring apps may have an impact on battery life and device performance, as they require continuous monitoring and use additional system resources. Therefore, it's recommended to use such apps sparingly and only when necessary.
If you suspect that your iPhone is overheating or experiencing temperature-related issues, it's advisable to contact Apple Support or visit an authorized service center for assistance and professional diagnosis.