You can, for example, check out a tool like BuzzSumo or SEMrush. BuzzSumo has a social search feature that helps you to identify what’s trending on YouTube. SEMrush offers intuitive keyword research tools that will help you to identify keywords which you can use as content ideas for new videos. Alternatively, you can simply use YouTube’s auto-suggest feature. It’s free and easy to use. Just type your topic or keyword into YouTube’s search field and YouTube will automatically offer suggestions.