You can find out which phones support DLE by searching in Bluetooth SIG's device list. This list has a registry of all supported features for Bluetooth devices.
To find out if your phone supports the Data Packet Length Extension, just do the following:
1. Search for the phone you wish to check.
2. Click on the Declaration ID.
3. Scroll down until you find View ICS Details and click on this link.
4. Click on Core Protocol Layers --> LL(Low Energy Link Layer).
5. Under Table 9: Supported Features you can check whether or not your phone supports BLE Data Packet Length Extension.
Note that this list only states which devices that have the capability to support BLE Data Packet Length Extension. HavingBLE Data Packet Length Extension implemented on the different phones is up to the phone manufacturer. In other words, you might find a phone on the list which does not work with the BLE Data Packet Length Extension.
