The examples show that the technology is in place to lock out websites.
Yes, they can block ip-addresses by interfering with the BGP 4 protocol on exchange point routers. I did see a whitepaper for this about 20 year ago when working for a Carrier. ISPs (internet Providers) are forced to peer with a government BGP 4 servers which holds a black-list. A black listed ip addresses route will then be pointing to a "NULL route" or similar.
This URL https://www.ashepostandtimes.com/ is reachable for me (from SE Asia).