As others have mentioned in this thread, it will really depend on the restaurant and the time of day you visit. Storybook Dining Dinner is going to be a vastly different experience than Crystal Palace Breakfast or Lunch. Storybook, Cinderella's Royal Table, and even non-character prix-fixe menu restaurants at WDW tend to rush us more than buffet or a la carte menu restaurants will. Storybook Dining was the worst at rushing us when we went in 2019, Garden Grill was the best at letting us slow down and enjoy the experience when I was there in 2020. Topolino's Terrace has been a mixed bag and we've gone once a year for the past three years.
In your case, I think the best way to control the length of your dining experience is to consider character buffets, as this is the only way to ensure you'll have full control of how long you wait in between plates. If you'd really rather do a family style meal like Garden Grill/Akershus or a prix-fixe meal like Cinderella's Royal Table, my best tip for you is to go at what we would consider an awkward dining time in America. An 11 AM early lunch or a 4 PM late lunch will be great for these places, as you can sometimes catch them when they're "slower" and there's less of a demand to turn over tables.
Have so much fun!