It might. A CT scan might. And it might not, as you are still quite young, so any damage might not show yet. The brain is a very hard thing to understand, and if you have no symptoms, even harder. There's no question that every blow we take on the head, whether it be falling down on it or heading a soccer ball or getting hit can take a toll, but individuals vary a lot one from the other and what it takes to harm one enough to notice it before we die can be completely benign to another person. If you have reason to suspect you have a problem, the only way to truly answer your question is to see a specialist and see if they are willing to give a test to someone who isn't exhibiting symptoms. If you're worried about it, though, every additional blow is an additional risk, so you do have an immediate way not to exacerbate the harm, and that's to find safer hobbies. Peace.
It might but they often do a PET scan. The problem with boxing, unlike other sports, is that it is repetitive injury to the head. So, it gets its own special category for brain injury that is sports related. Read in this article the section on boxing from a neurologists perspective. It's a rough one for brain injury. https://www.aans.org/Patients/Neurosurgical-Conditions-and-Treatments/Sports-related-Head-Injury Boxers, though, often have symptoms related to the accumulative effect of these blows. Speech issues, stiffness, trouble thinking, etc. This article is about those repetitive head injuries because of sports. https://www.mayoclinic.org/diseases-conditions/chronic-traumatic-encephalopathy/symptoms-causes/syc-20370921 They use the PET scan most and symptom questionnaires. They use some of the same biomarkers they use in alzheimers also. So, don't be afraid to ask to be evaluated. But, it is good news you have no symptoms at this time of an issue. Are you going back to boxing or have you hung up the gloves?