It really depends how much work you wish to put into it. Is your goal to make money off of it, or are you also seeking to produce genuinely good quality content? If you can find something tha strikes the right balance between a subject/theme that you actually enjoy covering as well as one that is popular, you will get a lot more out of it in terms of financial gain as well as not driving yourselffter a few months at best.
If you just want to make a quick buck, I suggest the following -- do some research into any of the innumerable 'top 10' or 'top 20' videos. Stuff like 'top 10 most insane daring jumps from high places' or 'top 10 creepiest unexplained disappearances' -- look over the way their videos are structured and take notice of something important (you can choose to sort by this option in the advanced search function on YouTube): check to see how the licensing on the video is listed. If you find stuff that has a Creative Commons (CC) attribution, which many of them will have, you are in luck. With CC stuff you are free to be able to use/reuse it and put it in your video in any way you wish. You can EASILY make a ton of videos on all sorts of different topics, just re-using existing footage from similar videos, splicing them up differently and changing the style/narration and transition graphics/overlays. See where I'm going with this? These videos will get you a TON of views and subscribers...the key to success on YouTube is CONSISTENCY.
Uploading videos at a regular pace on a schedule helps, The biggest grower on YouTube currently (and for the foreseeable future) is REGULAR LIVE STREAMING. If you do regular live streaming content (again, this is best left to those with a desire to actually be involved in the content creation process/those who feel comfortable being on screen or at a minimum, doing vocal narration while keeping themselves hidden, though this raises limitations to your live content) you can EASILY get a large following, provided you do so regularly and are decently entertaining. I was able to get to 20 thousand subscribers on a channel in less than 3 months JUST doing daily (M-F) livestreams where I did a daily breakdown of the news in the US -- mostly politics, some pop cultural stuff. Donations come pouring in through superchats (though YouTube takes a 30% cut and you don't get paid on these for over a month) but the money from streamlabs, paypal/cashapp donations, crypto donations, and merchandise purchases can bring in a pretty penny if you dedicate yourself to it. YouTube as a platform is kind of dying for any sort of content outside of the mainstream, however. I would suggest checking out a site like DLive which is growing at a breakneck speed and is in dire need of new, interesting content creators.
