IMO, economics is nothing but math applied to the study of resource allocation. Many on this sub might disagree, but I think the field is consistently moving towards accordance with this description. TBH, it seems to me that every field x tangential to applied math is essentially becoming "math applied to field x" (and increasingly, "Python applied to field x", as well). I'm not trying to be reductionist here, as there's certainly enough math focused on econ that you could consider it a completely valid and serious branch of math which necessitates its own study, i.e. it has idiosyncrasies and whatnot which are best mastered by specialized experts and not general applied mathematicians. That is to say, you don't have to be an applied mathematician to be an excellent economist, despite the increasing mathiness of the field.
So, if you're in econ, I think you should think of yourself as a flavor of mathematician. So, I'd definitely study up. You don't have to be a mathematical economist, but you should be literate in the lingua franca of the field. I believe this requires linear algebra, multivariable calculus (including differential equations), probability, and statistics, leading into real analysis, mathematical statistics, optimization, game theory, machine learning, and control theory at higher levels (which you may not reach or need, depending on what you do).
A great, though perhaps slightly advanced resource is http://quantecon.org
A great introductory resource is this Coursera course, which surveys the mathematical curriculum that Russian econ undergraduates generally complete by their final year: https://www.coursera.org/learn/mathematics-for-economists
As you can probably tell, the Russians are very serious.
Both of these resources are free.