Hi @elenahornfilm! Thank you <3
Well, it's easy to doubt that chess is a sport since it has no physical activity (at least not physical activity that we can see with the naked eye), but in reality the physical and mental fatigue that a chess grandmaster can have in a high-caliber tournament can be comparable to the physical expense that a bicycle rider makes in the Tour de France.
technically it is not a sport, but it is considered as such, look at this article: Is Chess A Sport?