If you find yourself asking if something might be shocking or jarring, it probably will be for some people. And it's helpful to give a warning to folks, especially since you never know what might be too much for another person.
I had a page with a disturbing scene, and I outright told the readers in the previous page to feel free to skip or scroll really fast if they didn't want to see it. Mainly because in previous, much milder cases, I had two readers express how just the thought of _____ makes them queasy. When said disturbing page came up, even the folks I knew were pretty chill with most violence were REALLY grateful for the warning.
So yeah. Warnings are good to have, cause at worst it's just an extra thing on top, and at best it gives viewers time they might need to prepare.