Link sUnderline dand Bold in Post content Only

I would like links in the content of posts to be underlined and bold. Not pages, not pages built with Beaver page builder. Not in the header. Not in menu links. Not in footer. Not in buttons (I don’t use buttons in post content). Just want to decorate text links in articles.

I tried using the CSS in the documentation. I tried 3 different CSS combinations and tried searching. Tried inspecting in Chrome and totally failed at figuring that out. Sorry if this is common knowledge but I can’t ever remember how to do this.