CORS is called as Cross origin resource sharing.
When we are call web API endpoints from React JS project there is a chance that you will be getting CORS issue.
You might have seen a lot of resolution which none of that working for you.
Here is the resolution to your CORS issue, You can enable the proxy setting and get rid of CORS issue.
Add one line in package.json file.
"proxy": "{Server URL}"
E.g.
"proxy": "http://127.0.0.1:8000"