I have a great deal of experience running various types of Google ads, including those that appear on YouTube as in-stream (often the ones you try to click away from after 5 seconds), in-feed (the ones you see in the upper right corner if you're on a desktop/laptop and under your video if you're on mobile), and search (the ones typically at the top of the search results when you search on YouTube). These ads also can appear in the Google network, which means on websites across the world.
How can these ads help you with your YouTube channel? They can help other people see your content that the algorithm wouldn't normally push. They can help people see your first 5 seconds to see if they want to see more (by the way, those first 5 seconds are free to you -- you only pay if they watch 30 seconds, the entire video if it's less than 30 seconds, or they "engage" with your "ad"). They can help you "prime the pump" by giving you an initial set of inexpensive views (which may or may not represent "social proof" -- the evidence that others might like your video that causes people to click and watch).
Will they get you subscribers? Maybe, if the people watching an in-stream continue to watch and really like your video(s). And in the case of in-feed/search, if they click on your ad and enjoy your video.
Will they get you views? Yes, but they're not likely to be views that convert into subscribers and long-term viewers, especially if you go the cheapest route.
I've used these techniques for clients, students, and my own videos. In the long-run, your content/personality/etc. has the largest impact. But in the short-run, ads can be effective and they don't have to cost a lot of money. If you're trying to stop smoking/drinking/Starbucks-ing/etc., you could use that daily money to fund ads and see what you get.
Tell you what... I'll make a video on this in the next few weeks and explain how it works, even with some how-to steps.
In the meantime, think about what you'll give up to start putting a few dollars a day into your videos.
Happy YouTube Growing!