curl --location --request GET '/rest/api/3/fieldconfigurationscheme/project?projectId'
{"isLast":true,"maxResults":50,"startAt":0,"total":5,"values":[{"projectIds":["10","11"]},{"fieldConfigurationScheme":{"id":"10002","name":"Field Configuration Scheme for software related projects","description":"We can use this one for software projects."},"projectIds":["12","13","14"]}]}