No, it doesn't automatically make it irrational.
A few counter-examples are shown here
- 0.37373737... = 37/99
- 0.1111111111... = 1/9
- 0.1666666.... = 1/6
Notice how when we have a repeating pattern of some kind, it leads to a rational number. A rational number is a ratio or fraction of two integers. The denominator cannot be zero.
An example of an irrational value is pi = 3.1415926535898... where there is no repeating pattern no matter how far we extend the decimal digits out. This means we cannot write pi as a ratio of two integers. We can get close with approximations like 22/7 and 355/113, but we can't get the exact value itself.