I use wired headphones with my iPad, but the sound is very low. It's like my voice is being picked up through the iPad speakers

Sounds like the iPad is not actually detecting the mic on the wired headphones.

Again, are you sure, these headphones have a microphone?

What make and model of headphones are these?

Are they Apple headphones?

How are they being plugged in to the iPad? 3.5mm port? Lighting to 3.5mm? USB-C to 3.5mm?

I'm sorry, your post is not very clear.

Speakers don't pick up sound. They make sound.

What exactly is low? The headphone sound?

Have you increased the volume, using the volume buttons on the side of the iPad?

Are you maybe saying that the microphone sound is very low?

If so, what kind of headphones are you using?

Do the headphones have a built in microphone?

If they do, is the microphone, near your mouth?

If they don't have a mic, then the iPad will use its own built-in mic, and if it's far away from you, it may not be picking up your voice well.

Please explain clearly and in as much detail as possible what sound is actually low.