Cook the pasta: Bring a large pot of salted water to a boil. Cook the pasta until just al dente, according to package directions.
Drain and rinse briefly under cool water to stop the cooking. Shake off excess water.
Make the dressing: In a large bowl, whisk together Greek yogurt, olive oil, lemon juice, ranch seasoning, oregano, and garlic. Add 1–2 tablespoons of water or milk to thin to a pourable consistency.
Taste and adjust with salt, pepper, or extra lemon.
Prep the veggies: While the pasta cools, chop the cucumber, tomatoes, onion, and bell pepper. Halve the olives and rinse the chickpeas.
Toss it all together: Add the cooled pasta to the bowl with the dressing. Fold in cucumber, tomatoes, onion, bell pepper, olives, and chickpeas.
Add feta and herbs. Toss gently until everything is coated.
Adjust and chill: Taste and season with more salt, pepper, lemon, or ranch seasoning. For best flavor, cover and chill for at least 30 minutes before serving.
Serve: Top with extra feta and herbs.
If adding cooked chicken, shrimp, or tofu, fold it in just before serving or portion it on top for easy macros.