If you are state-level actor wanting to censor, the ISPs in your country you will ask politely the large host (Cloudflare, Google, AWS) to cooperate and drop an

If you are state-level actor wanting to censor, the ISPs in your country you will ask politely the large host (Cloudflare, Google, AWS) to cooperate and drop any traffic coming for the censored domain from their IP ranges. Only if the large host does not cooperate, the respective ISPs will block their entire IP range, (if they want to keep operating in given jurisdiction).