It can’t do both at the same time.
By remapping I assume you mean changing the ECU (engine control unit) programming.
Depending on what all it controls, usually fuel injectors and ignition, and what it reads, air pressure, rpm, oxygen, throttle input, the mapping adjusts timing of ignition, and how much fuel is injected based on how fast the engine is spinning, and where the throttle is set.
Most cars from the factory have a very simple mapping based around what most drivers do.
A fancy prototype CRX I had back in the 90s had very custom mapping that meant when I drove mellow, it got about 45 mpg, but had very slow acceleration. If I pushed the throttle past a certian point, it spun up like a bat out of hell, but the fuel economy would plummet.
What you can do with custom mapping is change the way the engine behaves under various conditions and based on the inputs. There is no magic get more out of the engine. Want more power? Eat more fuel and lose economy, and likely not burn off all the fuel so more dirty exhaust. Want more range? Limit power and lose acceleration.
Anyone who hasn’t done a Mun landing shouldn’t get to direct space scenes.