How to display yellow strip at top of instance for any display of messages

Summary:

Requirement is to display important messages that will be available for every user of instance

Content (please ensure you mask any confidential information):

Hi, How to put the yellow strip at the top of instance for all users just like we see during sandboxing. Generally, I have seen people using it to display critical messages such as cloning date or instance update etc. Unable to figure out how to achieve this? It looks similar like below without any edit or drop-down options:

Version (include the version you are using, if applicable):

23D

Code Snippet (add any code snippets that support your topic, if applicable):