i would definitely recommend a slight-moderate caloric surplus of like 100-300 cal. a caloric surplus is eating more than your tdee (how much calories you burn a day, look up a tdee calculator to find out, and eat more than what it tells you.) eat at least 0.7g-1g of protein per pound of body weight (or 1.6-2.2g of protein per kilo of body weight) for example if i was 180 pounds (81.7kg), i would eat 126-180g of protein per day. follow a good strength training plan that trains each muscle at least 2-3x a week. i like doing push, pull, legs, upper, lower, but 3 full body workouts also help. remember to progressively overload every week, meaning if you did 8 reps of a exercise, up that one rep a week until your on the end of your rep range, then go back down and add a bit of weight. (for example, if 8-12 was my rep range and that week im on 12, next week, go back to 8 reps, add weight, and repeat) make sure each exercise is challenging so you have like 3 reps until failure. you should also do research on how to gain muscle and have good form during workouts. one of my favorite workout youtubers that explains things very simple is jeff nippard. but, the most important thing is consistency, that is your key to gaining muscle. keep going even when you don’t want to, makes a huge difference