Use of a screen protector is largely personal choice - but there are considerations.
iPad screens are robust, but the anti-reflection treatment and oleophobic coating can be easily damaged by tiny grit/dust particles that are unavoidable in many environments. The oleophobic coating is a chemical sacrificial layer that will wear-out over time.
A Screen Protector provides an additional defensive barrier - protecting both the original screen finish and the oleophobic coating. The downside is, perhaps, an increase in screen reflectivity and a slight reduction in contrast.
Consider that the iPad screen is the single most expensive component of an iPad - whereas a screen protector is sacrificial layer that is easy and relatively cheap to replace. Do you plan to use an Apple Pencil?
Whilst the Apple Pencil has a soft tip that is intended to protect the screen from damage, basic material science tells us that a hard abrasive material (such as grit), will embed in the softer of two materials. Once embedded, the very hard material can be repeatedly dragged across the screen - and cause damage.
A fingertip can easily “feel” grit an other abrasive contaminants - which you will instinctively not drag across the screen. When using a pencil, you cannot directly feel potentially damaging surface contamination.
The use of a screen protector is a matter of personal choice. Armed with an understanding of “how” a screen can be damaged will help you to make an informed decision.
Properly designed screen protectors from reputable manufacturers (e.g., Zagg and Otterbox - both with very good reputation) will not cause any performance issues with touch sensitivity, or if covering the camera, any discernible loss of image quality.