Drain and fill or full fluid flush

I have a 2008 with a automatic transmission, the miles are approx 76,000 but obviously it’s 18 years old. I’ve done at least one drain and fill since I owned it and was going to do another this week. I’m curious though if I should do a full fluid replacement, I don’t put a lot of miles on it and I haven’t towed anything. What do you guys think?