Trello (free version)
I love Structured. I have it sync between my iPhone and iPad. There is a feature on the iPad where you can make a list of tasks you need to do in your inbox. Then you can pull up your day beside it and plug those tasks into your free blocks of time. So I usually plan my day on my iPad the night before. I use my phone to send notifications to my watch to keep me on task. The app also has AI where you can tell it what you need to do and it will organize your day for you. However, you have to give specifics like how long the task will take. I find the drag and drop method I mentioned earlier works best for me.
Google calendar is the best 💯