@mrsbunny1003 Given the way your CPU and GPU are performing in-game, the next step is hardware monitoring. You can download hwinfo (free) from here:
https://www.hwinfo.com/download/
You don't even need to install; just grab the portable version, unzip it, and launch it directly from Downloads. (If you do want to install, be sure to click the green download button, not the orange one.) Restart your computer, launch hwinfo, and run it on sensors only. Click the icon that's a sheet of paper with a + sign on it to start logging. Wait five minutes, then launch Origin and Sims 4, and play for 20 minutes, then quit and end the logging by clicking the same icon.
You can upload your log file in .csv format to a third-party filesharing site and link it here. Or you can change its format to .txt (log.txt, not log.csv.txt) and attach it to a post here.