Yes and no. Conquest is certainly a tool that can help run a capitalist state. But same tool can be used by any other type of state with the same goal. We've been raiding the neighboring cave for mammoth meat long before capitalism was invented. The issue here is that a nation can boost its own economy through conquering foreign territory and add conquered resources to their own, and while it bares some resemblance to how a capitalist state is often based around resource extraction and exploitation, I wouldn't say it inherently means that a capitalist state must do so more than any other type of state.

As for your comment around scientific progress, there are pros and cons. Resources can be invested in a research program, but as long as this is left to the free market and free capital, the research will only be funded if there's a reasonable chance (or impression thereof) that the research can yield results that can be used for capital gain. However, a research project would have no problems finding investors if it appears to be worthy of said investment.