Can I also say that without "estas"? As far as I know it does not change anything, I believe I can make the same sentence if I would put "estas" between Cxu and tio
Well, one could say: Ĉu tiu besto sanktas? and you'd leave out the estas, technically. And, though the Holy Owl would complain, saying: Ĉu estas tiu… is not a crime. Heck, if you wanted to you could say: Ĉu sanktas besto tiu? and most experienced (and many non-natively anglophonic Esperantists of less experience) would understand it.
But the sentence does need a verb, and that is the function of estas in the example.
Mi nun anticipas la atakon de la sankta strigo. Kaŝu min!
Dankon Fred! I asked other Esperantists too in a whatsapp group and they basicly said the same, thank you for being everywhere on this course to help people with questions like mine!