Greetings, Plz confirm if IPAD Pro or IPAD Air could be connected to external Hard Drvie (1TB)

iPadOS provides limited support for external Hard Disk storage.

An external HDD can be connected to your iPad with the Apple adapter appropriate for your model of iPad - if the HDD is both partitioned and formatted appropriately (i.e., a single partition - formatted as FAT32, exFAT, APFS or HFS+). 

You should also note that the iPad is not capable of providing sufficient power to run an HDD. If the HDD does not have its own source of power - then external power must be supplied to the HDD using a connecting adapter (e.g., an Apple Lightning to USB3 Camera Adapter and Apple Charger of at least 12W) - or by connecting both the iPad and HDD to a powered USB hub.

If you iPad has Lightning Port, you will require a Lightning to USB 3 Camera Adapter:

https://store.apple.com/uk/xc/product/MK0W2ZM/A

If you have a 2020 iPad Air4, or a 2018/2020 model of iPad Pro with a USB-C port, you will in all likelihood need to connect both your iPad and HDD to a powered USB Hub with appropriate USB cables.

I hope you find this to be helpful in providing some useful clarity.

Yes, but not without some prelimary setup.

The drive may, or may not, need its own external power source as iPad do not have a powerful enough internal power supply.

The drive, itself, needs to be setup with a single partition and formatted in either Apple APFS or HFS+ formats OR Fat 32 or Ex fat formats.