Apple just introduced the third generation I Phone SE, and this model has significant improvements over its predecessors, which includes support for sub-6GHz 5G and A15 processor. This new model also boasts a longer battery life, which can be attributed to its physically larger battery. 

Apple has not  made any announcement  about the battery capacity, so it is yet to be seen exactly how long the battery is going to last. But if we compare the new SE's tech specs with the old one, it wouldn't be an overstatement to say that Apple is promising some new improvements and the results are impressive.

Apple saw some long lasting battery performance by putting bigger batteries in the iPhone 13 lineup, so it does not come as any surprise to see the Apple repeating the same strategy with the new SE.