Quick solve in the Preferences: Go to Viewports preferences, then check the box for Render using Anti Alias. Your system may have different graphics card hardware which allows for various levels of anti alias sampling. Check the preceding preferences page, Hardware Renderer, to select from the levels available. The highest setting is used here in the Bunker at 8x CSAA High Quality with the NVIDIA GeForce GTX 1650.
------------------------------
Austin
------------------------------