I’ve looked at the r/askhistorians book list and all of the listed books on Russia seem to cover the USSR, the Russian Federation, or the very end of the Russian Empire - and then pretty much exclusively the lead-up to revolution. What are the best English-language books on the empire itself - its expansion from Muscovy, figures like Ivan the Terrible, Peter the Great, Catherine the Great, and so on and so forth?
I really liked Robert Massie’s Peter the Great: His Life and World. Not only is it a fantastic biography of the tsar, I think it does a great job putting the reader in the world he inhabited (such as the international political situation of his time and the various other powerful monarchs he dealt with). He also wrote a book about Catherine the Great but I liked that one less for some reason. I’d still give it a try.