iphone se 2020 battery dies

I would recommend you go to Settings > Battery and look at what's using the most charge on your phone. If things are running in the background, do a better job of force closing things you don't need to have running.

There are many things you look at to see if you need them running. For example you may have location services turned on for all your apps. You don't need to have that. You may have your mail accounts fetching non-stop for new messages. See this link about maximizing battery performance on your phone --> iPhone Battery and Performance - Apple Support

Otherwise, you can certainly schedule an appointment at your Apple Store Genius Bar for evaluation. If after testing, it is determined there is an actual defect with your phone, Apple will surely replace it.

How recently did you get the new phone? It could still be indexing data if you restored the new phone from the backup of the previous phone.

I'd also suggest you do a simple Forced Restart on your phone.

Step 1: Press and release the Volume Up button.

Step 2: Press and release the Volume Down button.

Step 3: Press and hold the Side button until your device reboots and you see the Apple Log, then release.

Keep in mind that each button press should occur in quick succession, one after the other. During Step 3, after pressing and holding the Side button for approximately 10 seconds, the iPhone SE will force restart (hard reset).

This simple procedure may stop some things that have been running which didn't need to run and could solve this for you completely.