Artificially aligned or positioned functional materials are essential building blocks for modern devices and nanoelectronics. Since the emergence of 2D materials, the vertical stacking/integration of exotic materials has garnered increasing attention. However, controlling homostructures, e.g. identical materials conjoined with varying crystalline orientations, magnetism, or strain states, along the lateral direction remains challenging. Leveraging on the freestanding thin film growth techniques, the concept of twisted lateral homostructures has been introduced, enabling precise control over the lateral alignment of crystalline directions. Here, using La_0.7Sr_0.3MnO₃, a classic strongly correlated material, the precise manipulation of epitaxial strain alongside the homojunction is demonstrated. This leads to a precisely controllable lateral homostructure composed of polymorphic ferromagnetic and antiferromagnetic La_0.7Sr_0.3MnO₃ regions. It is further identified that the interactions between the ferromagnetic and antiferromagnetic regions of La_0.7Sr_0.3MnO₃ lead to unconventional ultrafast spin dynamics and magnetotransport behavior. The results provide a promising platform for developing novel emergent phenomena and functionalities in the twisted lateral homostructures.