Strength training bulks you up: true or false?

Both!
 
You don’t bulk up lifting 5 or 10 lb weights for 30 minutes twice a week.
 
Building muscle mass doesn’t just happen when you pick up weights; it takes a lot of effort, far more than most people are willing to do.
 
By adjusting the volume of training—the weight, number of reps, number of sets, and frequency—you can tailor an exercise program to bulk up. Or not. As you wish.
 
Building muscle mass, or avoiding bulking up, is something you can control.
 
After all, you don’t get a physique like this by accident.