When a puberty is complete does it make harder to become an athlete?

The answer is: no

During puberty, the body undergoes significant changes due to the increased production of hormones, such as testosterone and estrogen. These hormonal changes lead to physical development and growth, including increased muscle mass and strength, improved coordination, and enhanced cardiovascular function. Athletes often experience peak physical performance during late adolescence and early adulthood, which coincides with the completion of puberty. Therefore, puberty is generally not a limiting factor for becoming an athlete.