The recommended safe level for leisure noise is below 80 dB for a maximum of 40 hours duration in a week, according to the World Health Organization.3
Some devices like televisions or smartphones will allow you to set a volume limit. You can check your device's manual or settings to see if you can set up a volume limit.
On an iPhone, you can go to Settings > Sound & Haptics > Headphone Safety. Here you can enable the ‘ReduceLoud Sounds’ feature and set your volume limit to the recommended 80 dB. Your iPhone will analyze headphone audio and reduce sounds that are over the set decibel level.
You can also enable ‘Headphone Notifications’ to receive notifications informing you if you’ve been listening to loud headphone audio for long enough to affect your hearing. Your iPhone will measure headphone audio levels and if you exceed the recommended 7-day limit based on the safe listening guidelines set by the World Health Organization, a notification will be sent and the volume is turned down.3
It is also possible to set a volume limit on some Android smartphones. Go to Settings > Sounds and vibration > Volume > More options > Media volume limit > Toggle the button to ‘On’ > set the ‘Custom volume limit’ to no more than two thirds of the volume range.
These instructions may not work the same for everyone, depending on what exact phone and version of the operating system they use. If the above instructions do not work for you, you can try searching for your phone model + “set volume limit instructions” in Google.