What do you mean by "UFOs"?

If you mean are there things in the sky that people can't identify, then yes, they're real.

If you mean are there alien ships, then who knows? But the odds are exceedingly low that there are, and there is no strong evidence of them that I'm aware of, so if I were a betting man, I'd say "no".

The preferred term these days in non-tinfoil hat circles is UAP (Unidentified Anomolous Phenomenon) specifically to address the problem of these “things” being observed (and therefore possibly merely optical) phenomena that are not necessarily (and are certainly not verifiably) objects at all.

A more sensibly formulated question would be "What is your estimation of probability that some UFO's (or UAP's) are technological objects created by a non-human intelligence?".

Something is happening; they are interdimensional, they violate the laws of physics, they can be summoned with occult practices, they are demons.

https://vaticancatholic.com/ufos-demonic-origin/