You can in theory load the panel with as many breakers and as many amps as you can fit, because the main breaker (the 200 amp one) will trip if you exceed 200 amps total draw at 240 volts. Each individual breaker is designed to protect the wiring (not the devices) that are controlled by the breaker. As previously noted, you need to do a demand analysis to determine how many amps you can load onto the panel without creating a risk of tripping the main breaker due to overloading.
Overloading the main breaker will not damage anything, but would be quite annoying if you tripped it frequently.
Many older homes were wired with 60 amp service, and have in some cases 150 amps total potential draw. As long as you keep the total actual draw below 60 amps, they function fine. My house is wired with a 100 A main panel, but my total breaker capacity is about 200 A. Most devices never draw close to their rated capacity, i.e. my cooktop is rated at 50A 240 volts, but to get that I would need to turn on every burner full, never gonna happen. Ditto for the electric oven, 40A theoretical, never gonna happen.