If you’re concerned about the keys of your folio keyboard marking or damaging your screen, you might consider using a screen-protector on the iPad.
This will provide you with a sacrificial layer over your [expensive to replace] screen - that will protect it from damage from any abrasive contamination, such as grit under your finger (or Apple Pencil should you use one), or from anything touching the screen (such as the smart/folio keyboard or other case).
Screen protectors are generally available in two types - laminated glass or adhesive film. At present, being so new to market, options for the new 2018 iPad Pro models are somewhat limited. The best advice, should you choose to use one, is to buy a reputable brand with a good waranty and/or returns policy; avoid unbranded or cheap versions from places such as ebay - your expensive iPad deserves better - and with good brands, your iPad is more likely to function as it should.
As an example, Zagg, a well regarded manufacturer, produce screen protectors with one of the best return/repacement programmes of any if the suppliers; it is warranted for life - if you ever damage it, Zagg will replace it.