I would first install a SATA SSD to make it 10 times faster than using a mechanical and probably worn out HDD. I would make sure all drivers, especially the graphics, are updated directly from manufacturer's site, not Windows Update. I would then go to Settings, System, Info, Advanced System Settings, Performance and disable all visual effects (such as fades, animations etc). In Settings, Accessibility, Visual Effects make sure both Transparency and Fades are disabled. This should make a huge difference in performance, but of course don't expect to play modern games. It will be able to play older less demanding games, probably with most video settings to "low" or "off". I would try it to see how it goes before investing on a low factor discreet graphics cards. Have in mind that low factor cards (I hope this is the appropriate term) are entry level. You will see some improvement over the onboard graphics card, but don't expect miracles. Again you must keep most settings to "low" or "off". If you want to improve visual appearance of the game, start with the lowest possible settings (including screen resolution, there is no need to play 1920x1080, try 1280x720 or lower), and gradually increase a single setting a step at a time. Stop when you see the game starts to lag.
PS: I would also set all the power settings for maximum performance, never allow the system to sleep, never switch off the screen or the hard disk, disable screensaver etc, to further improve performance. Also do not install any third party antivirus, Windows Defender is light and does a good job. I would then disable some services (such as Google Update, Mozilla Maintenance) and all startup applications. The less they run at startup the better.
PS2: You can also enable Ultimate Power Plan (ultimate system performance), run the following command in an Administrator command prompt or Powershell:
powercfg -duplicatescheme e9a42b02-d5df-448d-aa00-03f14749eb61
Then go to Control Panel, Power Settings and select that scheme. This will force the CPU to always run at maximum speed (Turbo Boost always on), not only when enabled by the game.