Snippet placeholders/dynamic text

One of the things that I need to do with Snippets is to write dates in various formats. I would like to be able to write snippets that include placeholders such as: yyyy-mm-dd that would output the date for today (for example: today's date is October 29, 2025, the output for the snippet would be 2025-10-29.

I also want dropdown lists for example: Option 1|Option 2|Option 3. When this snippet is fired, I would like to be presented a dropdown where I choose from those three options.