It is possible but difficult at scale.

https://dl.acm.org/doi/pdf/10.1145/112600.112601

https://cloud.google.com/spanner/docs/true-time-external-con...

Read from every server is not necessarily possible, unless we assume no network partitions.

it violates the consistency rule. it must get the value that it was written

Unfortunately, timestamps are not immutable. The system clock can be miscalibrated or even deliberately manipulated. It is however something of an open question. CAP is still a bit lacking in terms of rigorous mathematical proof (albeit the arguments are pretty convincing).