Apple doesn’t offer any means to modify the coefficient of friction between the iPad screen and tip of the Apple Pencil. The only available methods to increase friction is to either use a third-party screen protector (that is designed to provide a rougher surface) or a third-party silicone tip-cover - such as proposed by your own post.
Higher friction screen protectors are available from multiple manufacturers. Some offer a thin film (e.g., Paperlike) or a more substantial plastic (e.g., Zagg - Glass Fusion Canvas)
https://www.zagg.com/en_uk/glassfusion-plus-canvas-ipad-12-9-pro