Solved. Thanks to a post by Ethan here: https://community.esri.com/t5/arcgis-desktop-installation/arcmap-crashes-on-startup/td-p/809687. The problem was caused by having 2 display drivers running and that caused some kind of conflict. Under the Device Manager, Display Adapters, I had an Intel and NVIDIA driver running. I disabled NVIDIA and ArcMap started working fine. I noticed ArcCatalog worked fine until I tried to preview an MXD, then it would crash. So did some more searching on that and found Ethan's post.
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