This study reports the experimental discovery of multi-step topological transitions among elliptic skyrmion, meron/anti-meron pair, and circular skyrmion phases in a centrosymmetric magnet GdRu₂Ge₂. Using resonant X-ray and neutron scattering experiments, along with electron transport measurements, the researchers found that this compound hosts periodic lattices of elliptic skyrmions, meron/antimeron pairs, and circular skyrmions as a function of external magnetic field. The diameter of these objects is as small as 2.7 nm, which is two orders of magnitude smaller than typical non-centrosymmetric magnets. The intricate topological magnetic transitions are well reproduced by a theoretical model considering the competition between RKKY interactions at inequivalent wave vectors. The findings demonstrate that even a simple centrosymmetric magnet with competing interactions can be a promising material platform to realize a richer variety of nanometric magnetic quasi-particles with distinctive symmetry and topology, whose stability may be tunable by various external stimuli. The study also shows that the observed magnetic quasi-particles have distinct topological charges, and the transitions between them are governed by the competition between RKKY interactions at different wave vectors. The results highlight the potential of centrosymmetric magnets for hosting complex magnetic structures and their applications in information storage and memory devices.This study reports the experimental discovery of multi-step topological transitions among elliptic skyrmion, meron/anti-meron pair, and circular skyrmion phases in a centrosymmetric magnet GdRu₂Ge₂. Using resonant X-ray and neutron scattering experiments, along with electron transport measurements, the researchers found that this compound hosts periodic lattices of elliptic skyrmions, meron/antimeron pairs, and circular skyrmions as a function of external magnetic field. The diameter of these objects is as small as 2.7 nm, which is two orders of magnitude smaller than typical non-centrosymmetric magnets. The intricate topological magnetic transitions are well reproduced by a theoretical model considering the competition between RKKY interactions at inequivalent wave vectors. The findings demonstrate that even a simple centrosymmetric magnet with competing interactions can be a promising material platform to realize a richer variety of nanometric magnetic quasi-particles with distinctive symmetry and topology, whose stability may be tunable by various external stimuli. The study also shows that the observed magnetic quasi-particles have distinct topological charges, and the transitions between them are governed by the competition between RKKY interactions at different wave vectors. The results highlight the potential of centrosymmetric magnets for hosting complex magnetic structures and their applications in information storage and memory devices.