Wondering if it is worth plunking down the 6 bucks (I think?) to get the WWE network.

Specifically, I wanted to research Stevie Richards' thesis that the Trish/Mickie James era of women had more 3D characters in the ring than current women's wrestling. 

Would I have access to those matches?

If you mean Peacock, I'd say so. The interface is a bit unwieldy and the ads are annoying, but you get all the old PPVs as well as old episodes of Raw and Smackdown. There's also a ton of non-WWE content to check out as well. Worst-case scenario, you cancel after a month and you're out six bucks. Alternately, Instacart+ includes Peacock membership and they offer a two-week free trial.

Yeah if you’re in the states it also means you get the complete premier league package along with NFL and soon the NBA.  So I’d say worth it.

I like Peacock and do think its worth it if you're at all a fan of current WWE. I don't watch the weekly TV often, but I still watch the PLEs and $6 a pop will always be a bargain to me because I grew when PPVs were $30 to $50. Also, as the poster above said, the library is deep relative to what probably 99% of fans could ever want to watch. Every WCW, WWE, and ECW PPV. Every RAW, Nitro, SmackDown, and Thunder, I think. Lots of ECW TV. A ton of Coliseum Home Videos. A ton of WWE documentaries and behind-the-scenes shows. A whole bunch of territory stuff, though, sadly, it doesn't seem like they're adding much older content often. If you haven't had access to the Network before, you're not going to run out of things to watch on it.

I'm also a Dick Wolf Universe fan - Law & Order, SVU, and Criminal Intent, specifically - so there's that too and the various Chicago franchises. Also, for comedy, I think Killing It, Bust Down, Paul T. Goldman, and AP Bio are worth watching and are/were exclusive to Peacock, if I'm not mistaken.

To answer your specific question, if it was a Trish or Mickie James match that was televised on SmackDown, RAW, or on PPV, it is on there.