The iPhone can connect to other wireless headphones, but you need to make sure that these headphones comply with the Bluetooth protocols supported by the iPhone, such as A2DP and AVRCP. In general, most wireless headsets support these protocols, so you can connect to your iPhone via Bluetooth. In addition, the iPhone also supports the AirPods automatic pairing function, which can be more easily connected to Apple's headphones. In short, as long as it conforms to the Bluetooth protocol of the iPhone, other wireless headphones can be connected to the iPhone.
My phone can be connected to other Bluetooth headsets, open the iPhone Settings - Bluetooth, click the Bluetooth headsets to be connected, and then it can be used.