The longer a similar bullet is in the same caliber, the higher the sectional density, and the better the penetration potential, assuming similar construction and expansion.
The 7MM Mauser & the 6.5X55 Swede both have a reputation for killing power due to their long heavy bullets with high sectional densities.
Whether that is why they do a good job can be debated for all time, but I have no doubt that the high SD's help.
But then again, I am a believer in heavier, well constructed bullets that pass through the animal doing a lot of damage all the way through, vs bullets that "expend all their energy in the animal" without passing through, which is a faulty premise, IMHO.
Yes, both can kill game, never say they won't, just expressing my preference, and which I believe is better.
To me, sectional density is something to look at when choosing bullets. Not everything by a long way, but something to consider when choosing between good bullets.