Is there a way to turn on find my device online through the apple account?

Yes.

Use Find My on iCloud.com Read about it by clicking on this link --> https://support.apple.com/explore/find-my

or go directly to Locate a device in Find My iPhone on iCloud.com - Apple Support

If Find My is not enabled on the phone it cannot be enabled remotely.

No.

Never knew. Must be new.

I didn’t see any way to do it in the documentation.

QuickTimeKirk wrote:

Never knew. Must be new.

Nope, never been possible. If it's off, there's by definition no way to communicate with the device. It would not show up in the iCloud website.

I didn't look at the link he sent.

I just trusted the answer.

QuickTimeKirk wrote:

I didn't look at the link he sent.

I just trusted the answer.

I clicked the link, and all it says is that you must turn it on with the device.

You're right, I missed the part where they needed to turn it on, not just use Find My online. Find My has to be set up on the device itself, and cannot be done remotely.