Does this sound correct?

Panels are rated using a Standard Test Conditions "STC" method, this is an artificial light test which establishes a standard which the industry adopts to provide information with which consumers can use to estimate power needs. https://sinovoltaics.com/learning-center/quality/standard-test-conditions-stc-definition-and-problems/  Because such a test is in a controled environment with perfect conditions, real world useage may differ. When modules are heated above the test temperature, 25°C/77°F  exposed to the sun for example , the wattage output will drop, when in extreme cold they can actually exceed rated output. Altitude also is a factor, at sea level the output would be less than the same module at 10 000 feet in exact same angle and day due to atmospheric difference.

Usually a percentage ~80% or 0.8, is used as a multiplier for general calculation, so a 100W module would in most applications will be assumed to produce 80W, however this is if perfectly positioned, the actual maximum will only be available for a short duration each day, as the earth rotates the angle of the sun will change, if plotted on a graph the output would be a logarithmic bell curve. Since seasonal angle changes due th the earth tilting on its axis, a perfectly positioned model on a particular day will only, theroriticly, products it's maximum output twice a year. Most fixed arrays are positioned to achieve maximum harvest when energy needs a the greatest, solar tracking will maximize harvest throughout the year at the expense of complexity.

So the  short answer is yes, on a particular day it is conceivable 200W STC could  produce only 118W, adjusting to achieve higher output on that particular day will only result in other days of lower output.