Hi Diana Vettori,
The ArcGIS Server component itself has no issues with the IP address changing. Provided you don't have any other ArcGIS Enterprise components referring to your ArcGIS Server by exclusively by its IP address, then there should be no issues.
So for example - if it's a standalone ArcGIS Server, then there should be no impact in changing your ArcGIS Server's IP address. Likewise, if the Server is federated with a Portal using the ArcGIS Server's hostname - there should be no impact to either Portal or Server if the Server IP changes.
If however, the ArcGIS Server was federated with the Portal using the ArcGIS Server's IP address instead of its hostname (which is a much less common configuration) then changing the IP address of the ArcGIS Server would likely lead to communication issues between the Server and Portal.
Hope that helps!
Regards,
James