If you have an idea in your head, someone probablyhad it before you. So, before building a new flow from scratch, you could look for an existing template. This will save you lots of time since the template will come with actions and a process flow that can then be modified or extended. It will also serve as a quick-start guide and a learning tool. Just as you can use flows created by others, you could submit your own flows to the Flow store. Your flow will appear on the gallery page if it successfully goes through the approval process.
You can sign up for a free Power Automate account at https://flow.microsoft.com. It has a free plan as well as business plans. Power Automate comes with most Microsoft 365 licensing plans. Refer to Microsoft Licensing guide for more details. You can download it from https://m365book.page.link/flow-licensing.
The free plan lets you run a limited number of flows until it expires...