You have to make the adjustment in your riding. The dumb trainer doesn't do it for you. So - Think of it this way - You are pedaling your bike on the trainer on the flats in zwift and you real MPH (bike computer) is 17 and your virtual mph (zwift) is 20. When you go up a zwift hill if you don't adjust your effort (17mph on trainer) your virtual MPH will drop to say 8 mph. But if you increase your real MPH/effort to say 20 mph then you will go up the virtual hill faster maybe a virtual 12mph climb. Your speed on the trainer and Island don't match but your effort in the real world impact your virtual speed.

Trainer road is similar. To ride at 150 watts it may be 15 mph on your trainer. When the target goes up to 250 watts you have to up your speed/power to match. This could be just raising cadence or shifting gears to increase speed/effort.

In both situations (Zwift or TR) you control the effort manually. Trainer road or zwift cannot force you to increase the effort. With a kickr/computrainer type trainer you have no choice. They will force a change in your effort to stay pedaling.

I use a power meter on a dumb trainer and this become pretty intuitive once you start riding. My body is so adjusted to the Zwift island topography that I instinctively shift, increase power, and lower my cadence on the climb. Nothing physically changed in my bike, PM, or trainer. I just naturally simulate the climb with my adjusted effort.

So something has to be "SMART" in the mix. Either you have to use your actions to control the resistence to match conditions (dumb trainer) or you can use a Smart trainer and then you can just ride and shift/adapt to what the trainer does.