On Ebay, I bought a cell phone with FM radio, that gets the radio from
local stations, not from cell phone data, and after I bought it, I
found the manual online, which says that the radio antenna is the wire
to the earphones.

But the phone didn't come with the factory earphones.

Mostly I want to listen to 88.1 Mhz FM, and if possile 88.5, and
90.1frequencies.

For antenna purposes and those frequencies, are there any differences
from one headset to another?

Does the thickness of the copper wire matter?

Factory headphones may be impossible to get. without buying a second
phone. Should I try to find out how long the wire is on factory
earphones and get a headset with the same length?

Thanks.