That's called load following. That's also a thing a liquid fueled reactor can do that a solid fueled reactor can't.

doesnt make a difference to the economics of a nuke plant. Fuel consumption is a tiny fraction of the cost of nuke power, its almost all fixed cost - amortized construction costs, operations, etc. You need to run it at as close to 100% always to have any chance at payback & economical $/kw. Thats why they arent getting built.

You need to go tell the French that what they've been doing for decades isn't possible, then.

EPR has shown that the French have lost the ability to build reactors rapidly and on budget.

No, it's the opposite: https://en.wikipedia.org/wiki/Demand_side_management. Load-following is a good property for a power plant to have, though, especially if the plant is suitable for baseload generation.