Trying to find a laptop that will play Sims 3 well on high settings and will run fast is going to be tricky for under $800.
Here are some suggestions:
Dell - Inspiron 15.6" Laptop - Intel Core i5 - 8GB Memory - NVIDIA GeForce GTX 1050 - 1TB + 8GB Hybrid Hard Drive - Black
Price: $799.99
https://www.bestbuy.com/site/dell-inspiron-15-6-laptop-intel-core-i5-8gb-memory-nvidia-geforce-gtx-1050-1tb-8gb-hybrid-hard-drive-black/5709801.p?skuId=5709801Acer Predator Helios 300 Gaming Laptop, Intel Core i7 CPU, GeForce GTX 1060 6GB, VR Ready, 15.6" Full HD, 16GB DDR4, 256GB SSD, Red Backlit KB, Metal Chassis, G3-571-77QK
Price: $1,049.99
https://www.amazon.com/Acer-Predator-GeForce-Backlit-G3-571-77QK/dp/B06Y4GZS9CRecommended specs or better will not only load the game onto the computer, it will be able to be played on medium up to ultra settings (depending on game settings/preferences and system components). It will also be better at handling whatever downloadable content (DLC, expansions, etc.), custom content, and mods you have.
If you want to do some searching for yourself, see the specs below:
Laptop Specs:
Processor : i7 HQ or MQ quad ~ 2.4 GHz
Video card : Nvidia GTX 960m or better
System Memory: 8GB
Hard Drive Space: At least 500 GB
Windows 64 bit
Laptop hardware is much weaker than desktop hardware. You need a much more powerful laptop to equal the requirements on desktop. A laptop that meets requirements maybe more expensive than a desktop. - Laptops can not be upgraded you are stuck with the specs you buy.