Does it support 5G?

Yes it supports 5G.

Does the phone support fast charging? Or Does it have a fast charger In-Box?

Yes, the phone supports fast charging, and it does have a 33W fast charger Inside the Box.

What are the contents inside the box?

The contents inside the box are- Handset, Earphones, Protective Case, Documentation, USB cable, USB power adapter(33W) and a SIM ejector Pin.

Does the phone have a dual sim? Or does it have a hybrid sim slot?

Yes, the phone does have a dual sim feature, but it does not have a hybrid sim slot.

Does it have a 3.5 mm headphone jack?

Yes