The Xenyx 302 and 502 models do feature phantom power for powering microphones. However it should be noted that they do not have full 48 Volt phantom power supply, they have a 15 Volt phantom supply. 15 Volts is normally more than sufficient for powering a lot of microphones on the market (that require phantom power) but in some cases this will not be sufficient. The way to find this out is to check the specifications of the microphone you have purchased which will state the supply required.
If a microphone does require the full 48 Volt Phantom Power supply it may still work on the Xenyx 302 or 502 but with some limitations, for instance as the full power is not present it may reduce the headroom of the mic and also reduce the frequency response range.
A simple and cost effective solution should you require full phantom power with the Xenyx 302 or 502 is to use a Behringer PS400 supply box, simply plug into the PS400 using an XLR cable connected to the microphone, then use another XLR cable from the PS400 into the mic input of the Xenyx mixer.
Please see the link below for further info on the PS400: