Advice for a new guy

Hey everyone, just bought this Mid-2012 MBP for really cheap out of curiosity and it came with Sequoia, it’s quite smooth but apps take a while to open up and there are occasional slowdowns. I have ordered 2x8GB RAM to upgrade but I’m wondering if I should try a fresh install of Sequoia or Sonoma to improve responsiveness and make it a bit more snappy. Any tips appreciated as this is my first ever Mac device. Thank you!