Q: How can use bluetooth with iphone 6plue ?

Very vague.

What bluetooth device are you trying to find?

What have you tried?

What happened?

many bluetooth devices needs to be put in pairing/ discovery mode in order to connect with a device they have not paired with before read the manual of the bluetooth device how you do that

and this is what the ios devices support in terms of bluetooth profiles out of the box

iOS: Supported Bluetooth profiles - Apple Support