In these proceedings, we present the measurements of neutron skin thickness and nuclear deformation using isobar $^{96}_{44}$Ru+$^{96}_{44}$Ru $^{96}_{40}$Zr+$^{96}_{40}$Zr collisions at $\sqrt{s_{_{\rm NN}}}=200$ GeV by STAR detector. The significant deviations from unity ratios elliptic flow $v_{2}$, triangular $v_{3}$, mean $p_{\rm T}$ fluctuations $\langle\delta p_{\rm T}^{2}\rangle/\langle...