As others have said, "tone" is a fairly nebulous usually-female-oriented term that really means decreasing bodyfat and building muscle.
For the decreasing bodyfat side of the equation, you need a calorie deficit. 500kcal/day deficit is often recommended (works out to losing about 1lb/week). That can be accomplished by a number of methodologies, whether it's strict calorie counting, keto, general LCHF, paleo, vegan, low-fat, high-protein, intermittent fasting, 30 bananas a day, Slow Carb, whatever. The buzzwords don't matter, results do. Any of the trendy diets (healthy or not) if successful all end up a calorie deficit. Do what works for you and what you're comfortable with. Personally paleo-ish loose LCHF with as many vegetables as possible, a focus on nutrient-density, zero snacking or sugar, plus some intermittent fasting does the job. If you're hungry all the time, you're doing something wrong. Strength training here ensures that you're mostly losing bodyfat instead of muscle.
For building muscle, you need strength training (whatever kind you land on, barbell squats, deadlifts, and the like is where I'd go) paired with a calorie surplus, and a little extra protein. You don't need to go full gym-bro slurping down protein shakes all day, a small surplus is fine. You'll know while working out if you're not eating enough.
As a beginner, you can do both (lose bodyfat and gain muscle while eating essentially at maintenance) but you'll hit a wall in either direction at some point and that's where typical "bulk/cut" cycles come into play. I've noticed people tend to go overboard and gain way too much weight on a "bulk" and then have to lose too much on their "cut." Just alternate every so often focusing on one over the other. Focus on increasing your lifts while "bulking" and focus on a calorie deficit and maintaining (and not adding to) your lifts when "cutting" and you'll maintain progress in both directions.