Laying out my page posts new and old

OK I am incredibly new here.
I tried to look for this issue but wasn’t altogether sure what it would be called.

I have two questions.

In order to keep the new posts clean, I would like each post to only show the title and a paragraph or so and then have a choice to read “More” which can be clicked on to read the full post. I am using a theme called pixel. I have seen this done on other blogs.

I have figured out how to change font sizes using style.css after changing write permissions on the server. So that part I understand. Just not seeing anything which gives me the above mentioned functionality. Would it be a plug in? If so which one/s?

My second question is about how to keep the main post page short by rotating older posts out to other categories which are then listed by the months and years they were written in. I have built regular html sites with hundreds of pages in the past but so far no experience with this kind of on the fly stuff.

https://thechurchofdave.com/blogs/ Is the mostly empty page I am working on and I am a comedian with some pretty salty language so if yer easily offended you may not wanna go there. There are no inappropriate pictures though so it’s work safe/ish.

Any advice of help on this project is greatly appreciated and possibly even credited.

Thanks
ScaryDAve