They already did this, its no surprise. A guy ranked around 210 (over 200) played both venus and serena williams the same day, back to back matches, and crushed both of them.
https://www.youtube.com/shorts/JZzP8V9cHJc
You are correct. His name was Karsten Braasch - a name only the real tennis nerds ever heard of. He was mainly known for his strange service motion. This is what Wikipedia writes about the matches between him and the Williams sisters in 1998:
“Braasch competed in a “Battle of the Sexes” contest against the Williams sisters (Venus and Serena) at the 1998 Australian Open when he was ranked 203. Braasch was described by one journalist as “a man whose training regime centred around a pack of cigarettes and more than a couple bottles of ice cold lager”.[4] He nonetheless defeated both sisters, playing a single set against each, beating Serena 6–1 and Venus 6–2.[5] Braasch was thirty years old at the time, while Venus and Serena were seventeen and sixteen, respectively.”
Braasch also made headlines as he played the two matches after finishing a round of golf and drinking two shandies. (Shandy - absolutely vile! Why didn’t he just stick to proper beer??)