My 2-year-old rescue barks and lunges at every dog we see on walks. I don't know her history but I assume she had a bad experience. Will she ever be able to wal

Maybe, but it'll take 3-6 months of consistent work. You're probably right that something in her past wired this response, but the cause doesn't matter for training — the protocol is the same. When you see another dog, create distance immediately before she reacts. Cross the street, turn around, duck behind a car. Get far enough away that she notices the dog but doesn't lunge — for most reactive rescues that's 50-100 feet initially. At that distance, feed high-value treats continuously while the other dog is visible. Stop when the dog disappears. You're counter-conditioning: other dog = good things happen, not a threat. Repeat this 10-15 times per walk for 4-6 weeks. Slowly decrease distance as she stays calm. If she lunges, you're too close. Back up and build more reps. Most rescues need 100-200 repetitions before they can pass a dog calmly at 10 feet. Don't let her greet dogs on-leash during this time — it muddies the training and can trigger a reaction.