设\(f\left(x\right) \)是定义在\(R\)上的偶函数,对任意\(x∈R \),都有\(f\left(x-2\right)=f\left(x+2\right) \)且当\(x∈\left[-2,0\right] \)时,\(f\left(x\right)={\left( \dfrac{1}{2}\right)}^{x}-1 \)若在区间\((-2,6] \)内关于\(x\)的方程\(f\left(x\right)-{\log }_{a}\left(x+2\right)=0\left(a > 1\right) \)恰有\(3\)个不同的实数根,则\(a\)的取值范围是\((\) \()\)