Yes, Nokia 2 does have the dedicated MicroSD card slot.
Yes, Nokia 2 is a VoLTE mobile phone.
Nokia 2 has IP52 drip protection. That means it can withhold minor water pouring. But you need to be careful as the device also has the 3.5 mm jack and water can damage the phone.
No. You cannot record 4K videos from the Nokia 2.
It's not a bad phone, this Nokia 2. It's just that there's only so much you can do within a budget this tight.