OK, I know this doesn't make sense, but set your cellular to use only 3G. Even when you are using WiFi. It will make huge difference in battery life. : r/GalaxyS21
What takes more battery life, between 3G and 4G? - Quora
Two Way Radio 3500mAh Battery Inrico B-87c for 2g/3G/4G Inrico T320 WiFi Walkie Talkie - China Two Way Radio 3500mAh Battery and Inrico T320 Battery price | Made-in-China.com
Is 3G More Effective Battery-user Than 4G? - January 2024 | MyAmplifiers
2100mAh B9010 Battery For B9010 4G Wifi Router Mini 3G Lte MIFI Router Hotspot Modem High Quality
consumer products - Wi-fi is more power-efficient than 3G? - Skeptics Stack Exchange