Last modified datetime and published date

I am not sure if someone has already asked for this feature. I am not sure if this feature already exists. I looked in documentation and looked in Github issues, unable to find it,

We would need to have a automatically generated value of last modified date-time. And also a fixed value of published date-time. Such metadata is valuable.

This will be a useful information in cases of blog, seo, etc.

I have considered adding a date-time field in the configuration, but that can be a waste of time for the end user and manually adding can case issues on seo if the value is incorrect.