@Maninha First, the easy parts. A Sims 3 crash log is mostly useless, but it does have one helpful feature:
Total physical memory: 13234 Mb
Available physical memory: 9796 Mb
Total page file memory: 29618 Mb
Available page file memory: 23485 Mb
Total virtual memory: 4095 Mb
Free virtual memory: 1789 Mb
This is a report of the RAM use, from the game and overall, at the time of the crash. You can see that there was more than enough physical memory available for the game plus a buffer (9796 is far more than 4096), and that the "free virtual memory," which is how the game reports its own memory use, is nowhere near the limit. Anything above 500 MB means the crash was likely not memory-related.
Please repair the game in the EA App (Sims 3 > Manage > Repair) to undo the changes you've made to the .ini file and anything else. There is, somewhat surprisingly, a lot of misinformation still floating around about which values in which files correspond to what and how far they can be pushed, or whether changing them does anything at all. It's best to run the game in as close to a default state as possible while troubleshooting.
For the record, there's no way to force-limit Sims 3 to using 4 GB RAM, or to make it use more. And the default texture memory is 32 MB if the game doesn't pick up the GPU's VRAM on its own, which it usually doesn't with newer devices. The default of 2048 you found a reference to is either something else or not a default at all. Besides, since Sims 3 can only use 800 MB VRAM, seting the value higher than that has no practical effect.
For the issue itself, two of the Sims 3 errors in your dxdiag are crashes of the AMD graphics driver. Two are breakpoint errors, which have several causes, one of which is an issue with the graphics driver. So that's the place to start: with a clean uninstall and reinstall of the driver. Here's how:
https://crinrict.com/blog/2019/02/clean-re-install-of-graphics-drivers-with-display-driver-uninstaller-ddu.html
You can get a fresh copy of the newest driver from AMD here:
https://www.amd.com/en/support/downloads/drivers.html/processors/ryzen/ryzen-5000-series/amd-ryzen-7-5800h.html
Run the installer as an admin: right-click the download and select "Run as administrator." Restart the computer afterwards and before trying to play.