The two biggest power consumers in that system will be the GPU and the screen -- and neither of those is required for general office productivity or web browsing.  Unless you are also going to be using this as a multimedia workstation, order a system with Intel integrated graphics and an FHD screen and you will see good to better than good battery runtimes. Ordering a system with the 3K screen and a discrete GPU is pushing toward high performance -- and that's at odds with battery runtimes.  You can't buy a car with a high performance, turbocharged V8 engine and expect good fuel economy -- same here. Unless you're looking for some other application, you'll do better with a mainstream system, integrated GPU and FHD screen if you're looking for battery runtime.  
I'm currently working on a 7510 Plus (Manufactured 2022) and it has the 56Wh battery. Moving the bightness to 50% means I can get about 3 to 4 hours ish battery. Considering I would need to put more RAM in it to make it useable, an option is to return it to Dell and get the Insprion 7610 Plus as it has a 86Wh battery. However, I spotted it comes with a 3K screen which could hoover up any extra capacity. Is this the case or do users find it lasts say 5 hours plus when used for word processing, web browsing and so on. I get this is a "piece of string" type question but it will help whether I bite the bullet and upgrade my new Inspiron (which does have some benefits) or return it. Edit: Specs Inspiron 15 Plus 7510, 56Wh Battery, Intel I7 11800H, NVIDIA 3050 Ti, 8GB RAM. Usage: general office/productivity.
Inspiron 7610 Battery Life - Is it Any Good