We’re dealing with an imprecise question about a trait that is hard to define. The OP can either be tossed as unanswerable or we can try to narrow the parameters to provide “an” answer that may be unsatisfactory in many ways yet still shed some light. This isn’t unusual in questions here.
Look again at the actual OP.
Two parameters emerge immediately. One is that the entire New World is being looked at. The other is that the time period is narrow. When was the height of the slave trade?
That appears to put it between 1790 and 1830. Using 1800 is a convenient year.
That also means that we don’t have to worry about the spread of genes throughout the population for the past 200 years. In the 18th century social sanctions and control of slave populations reduced opportunities for contact. The possible contacts are also limited to just a few generations. All of this puts severe limits on the number of descendants.
Social factors in fact place boundaries on all the data. Race is a social construct, we know today, and then it was purely one since they had no understanding of genetics. Descendants of African slaves were also considered African slaves, even if a settler or indigenous native were part of their ancestry. (As always, this is not 100% the case but the small exceptions wash out in the general rounding.) The distinctions made by people at the time or calculated by historians or anthropologists since cover the vast majority of the population.
How are these calculated? That’s the much harder question. Some census data existed. The first U.S. census was 1790. Unfortunately most Latin American countries did not have censuses until later. Estimates must be made, which leads to wide error bars. It’s easier to concentrate on a single country’s history, obviously, and estimates for larger areas are built up by adding up the estimates for individual countries, which results in an even larger spread of estimates. However, this is a specialized academic area that has been systematically combing through all available numbers for a generation of scholars. Like any other area in science it has disagreements about specifics, but the numbers can’t be dismissed out of hand.
If it’s even approximately true that 18 million people counted as indigenous natives lived in the New World in 1800, and only 10.7 million African slaves had been brought in total, with many of those after 1800, then it seems implausible to suggest that the total number of living Africans and their descendants was larger than the total number of living indigenous natives and European settlers combined.
If you consider the question unanswerable, that is a legitimate position by today’s standards, although people living in 1800 would not understand how you could say such a thing. Conversely, analyzing what people living in 1800 would have said on the subject is an answerable question, if only tentatively. And that answer is “no.”