How to recover iCloud account without trusted number?

That telephone number does not match the trusted telephone number of the Apple Account involved.

Without that telephone number for the Apple Account involved, that Apple Account likely won’t be recoverable.

If there are devices associated and you want to try to recover access to those, you’ll need original purchase receipts and assistance from Apple: How to remove Activation Lock - Apple Support

If some Apple device is locked to an Apple Account that you don’t know and don’t control, the device will remain inaccessible.

If you no longer have access to the trusted telephone number for texts or for voice calls:

How to use account recovery when you can’t reset your Apple Account password - Apple Support