Game boosting apps are completely useless, they do nothing except shut down some background apps. And that’s something Android OS can handle very well on its own.
Some phones have built-in, or at least vendor-provided tuning apps. On Samsung phones, you have the older (and better) Game Tuner for fine tuning cpu performance, on more recent OS versions only the Game Launcher, which offers a performance preset. This will keep the cpu at higher clockrates, and thus reduce downclocking at the expense of battery life. Dosbox utilizes only one cpu core, so it can suffer from automatic downclocking, or even downshifting to an energy saving core. The improvements can be huge, as you can see in the benchmark chart on this forum.