You will have to call request release with releaseStartMetadata object and Poject ID or project name
This would be equivalent to the rest call - https://learn.microsoft.com/en-us/rest/api/azure/devops/release/releases/create?view=azure-devops-rest-6.0
let requestedRelease: ReleaseStartMetadata = {
definitionId: this.releaseConfiguration.pipelineId, // Sets definition Id to create a release.
description: this.releaseConfiguration.description, // Sets description to create a release.
isDraft: false, // Sets 'true' to create release in draft mode, 'false' otherwise.
manualEnvironments: new Array<string>(), // Sets list of environments to manual as condition.
properties: {},
reason: ReleaseReason.ContinuousIntegration, // Sets reason to create a release.
//artifacts: releaseArtifacts // Sets list of artifact to create a release.
// environmentsMetadata?: ReleaseStartEnvironmentMetadata[]; // Sets list of environments meta data.
// variables?: { [key: string]: ConfigurationVariableValue; }; // Sets list of release variables to be overridden at deployment time.
};
console.log("Requesting release");
let curRelease = await releaseApi.createRelease(requestedRelease, this.releaseConfiguration.projectId);
if (release != null) {
log.LogPipelineTriggered(pipelineName, projectName);
log.LogPipelineTriggerOutput(release);
if (release != null && release._links != null) {
log.LogOutputUrl(release._links.web.href);
}
}