Infinix made an ultra-thin entry-level phone, and it has a 5,160mAh battery: The Hot 60 Pro+ is just 6mm, gets the basics right, and it costs just $200
The Hot 60 Pro+ is the thinnest entry-level phone around. https://www.androidcentral.com/phones/infinix-hot-60-pro-plus-budget-phone-sleek-design?rand=7