Who wishes that there was an option for paragraph rules in PowerPoint?
Yeah, me too. While I don’t have an option that works all of the time for you, I do have a few hacks that will get you what you want.
I recently had an ask to recreate a case study document in PowerPoint. It had a pull quote and a fancy headline formatting that I needed to make as easy as possible for the end user to use and not mess up:

Adding the top rule as a static line works fine, but when you need to have one on the bottom that moves with the text, well, that one is tricky. What made this particular as even more technically challenging was that the rules were short and didn’t span the whole length of the text box.
Here’s how I did it with the text top-aligned in the text box (for bottom aligned, reverse the kinds of paragraph rules)..

1. My top rule is a simple 2.25pt line
2. While working on the master slide layout, I added a text placeholder and formatted the text accordingly.
3. Make sure the placeholder is set to “resize shape to fit text”
4. For the bottom rule 
   • select the text placeholder
   • Go to the Format tab
   • Click on the Edit Shape drop down
   • Choose Change Shape
   • Choose “Callout: line with no border”
   • Select the callout line and format it the same as your top rule.
   • Move the callout line in position at the bottom of your text box to match the length of the top line.
5. Now you have a pull quote box that will move the bottom line as you fill it with text.
6. Note that it will end up moving far from the text as you fill it.
7. To fix this, simply adjust the height of your text box.

Be aware that if you change the WIDTH of your text box, the bottom paragraph rule will also grow. However, you can manually adjust this on the slide.
That was one of two things I had to recreate. I thought I was done at that point. However, let’s take a look at what happens when you have a master layout with this paragraph rule style with an image placeholder behind it.
This is what I needed the final product to look like on the slide:

I applied all of the same trickery to this treatment. And was very pleased with myself until I switched from the master to the slide and saw this:

Because the top line is static, the placeholder always shows over top of it on the regular slide.
However, if you make the top line a placeholder on the master (I chose picture placeholder) and tweaked it a bit, it will always be on top. The only thing you have to remember to do on the main slide is to send the image to the back after you’ve filled the picture placeholder. And, voila! You have the desired paragraph rule style.
My settings for the rule made out of a picture placeholder are as follows:

• Font size: 1pt
• Font color: same as fill color
• Text box margins all zero
• Placeholder height to match MY rule ended up being 0.03inches for a 2.25pt line