On occasion, it helps to remember when something was written or said.
As for the Old Testament, and for the time of Christ. fire was both extremely necessary and extremely dangerous. a to the danger: being burned seriously is generally considered to be one of the most physically painful things one can endure; ;and 2,000 years ago and more, if one was burned seriously over a significant part of the body, one was going to die, and in extreme agony.
The fires of hell are a metaphor for the extreme pain of separation from God. Souls have absolutely nothing upon which a physical reaction can occur. Show me a soul, and I will show you how it can be burned; but I am not going to wait around.
In apparitions, people are given visions of souls on occasion. But souls have no materiality, so what the “see” is a vision; not a “thing”. What they see represents the soul of the individual(s).
Asking the question “is there really fire in hell” is like asking if Balaam’s ass realy spoke. It is the wrong question. The Church recognizes that there are multiple literary forms used within Scripture; attempting to take everything as strictly literal is both mistaken, and misses the point of the passage.
Note: I am not saying that nothing is literal. But if you think about what fire meant to Jews (or anyone else, for that matter) 2,000 years ago, one does not need to go into all sorts of contortions trying to parse out whether “fire” in hell is literal, or whatever… And just as there is physical pain from a burn, so there is psychological and spiritual pain which can be intense. Fire, however, was a very effective metaphor for conveying the psychological and spiritual pain of separating from God.