yes, adding onto be's post, for the chiefing to be worth it strictly in terms of resources then you need to estimate the resource value of the village you're conquering (fields + buildings), subtract it by the cost of conquering from where you currently are (academy + research + chief) and see if that's higher than the negative cost of 3 settlers.
Assuming you have all the other prerequisite buildings for a chief then for the chief to be worth it:
(conquering: target village worth - lvl 20 academy - chief research - chief) > (settling: - 3 settlers)
And even if it's not worth it in terms of res, it might be worth it to save you time. Especially in the later stages of the game where settling becomes less and less desirable due to the time it takes to get the village up and running compared to if you had even a 300 pop head start.