I often use my own previous videos, as strange as that may seem to detect trends. Especially if I can see a pattern in videos that did well, it can help me to reproduce the success. One trend ( not like a new "trending" topic, but something that produces above average views) for me have been giant card videos for the game I play. I saw this trend in previous videos looking at the ones that did better than average and I have made a whole series because of noticing that trend. Almost all of those videos have done quite well for me.
You can also look through other channels in your niche and look at what videos they made recently that seemed to do better than their "average". Sometimes there may be a way for you to make something similar and feed the same demand or get suggested on their video. I think this is one of the maybe best ways to find trends. This is the most powerful if you see it happening for a smaller channel because a larger channel doing the same type of video can get get more exposure than the original person got. It's all about seeing demand that is outside of their normal views and think about where is that coming from.
Other trendy topics can be obvious or anticipated, like the game I play on my channel just had an update and I instantly know things related to the update that will be trendy because they are new and people will want to see videos about them. I also have knowledge about what my audience likes, so I can mix the new update content with videos on my channel that are proven trends like what I mentioned above.
I think to catch the most explosive trends, unless you are really lucky or use personal knowledge to anticipate what people might like... I think you want to look for other people who caught trends and then follow up on that. The trend I mentioned catching someone else had already had success with but I thought they hadn't fully filled the demand for it. I'm not talking once everyone and their mom has made a video, I mean like you see one or two smaller people have surprising success with it.