How do I lose the weight + stay/get thick?

Upon what little research ive done, I’ve heard that instead of doing cardio, weight training is best for maintaining/getting a thick lower body (ass, thighs) and losing the upper body weight. Is this true? How did you do it?

My goal is to lose weight entirely, yet stay thick/get thicker in my ass and thighs without gaining noticeable muscles in my arms, which I fear with lifting weights.