Click here https://developers.arcgis.com/dashboard/ (must login Arcgis online) to get your API key
Palm Springs CA API key
Every arcgis online account has its own set of api key. Here is api key by USGS acount
Here is api key
How do I get an API key
https://developers.arcgis.com/faq/#services-api-keys:~:text=How%20do%20I%20get%20an%20API%20key%3F
https://support.esri.com/en-us/knowledge-base/how-to-view-all-the-api-keys-in-your-arcgis-online-orga-000029113
Why you need ESRI api key anyway?
Generally you do not need api key except when you need search address
This example search address requirs ESRI api key
https://transparentgov.net/json2tree/datahub.io/hrsa/byaddress.html?backgroundlayerurl=https%3A%2F%2Fgisportal.hrsa.gov%2Fserver%2Frest%2Fservices%2FAnalyzerTool%2FAnalyzerTool%2FMapServer%2F1&search=24776+hidden&select_level2value=4