In standard formats (like OU, Ubers, etc.), Cinderace is unviable. It finds itself in a position where it is too good for OU, but not good enough for Ubers. Because of this, Cinderace finds itself rather unviable.
However, in other still standard formats, Cinderace is extremely viable. One of these is Monotype. Cinderace possesses a great Speed and Attack stat which allows it to cripple opposing mons. Cinderace is the only S ranked Pokemon in the Fire Monotype Viability Ranks.
Cinderace is also great in Battle Stadium Singles. Combined with Gigantamax, Cinderace's damage output combined with the ability to increase Attack and Speed make it overwhelming. It is also S rank in this tier.
These are the only formats in which Cinderace is viable.
Source: https://www.smogon.com/dex/ss/pokemon/cinderace/monotype/
https://www.smogon.com/dex/ss/pokemon/cinderace/battle-stadium-singles/
