curl --request PATCH \
  --url https://sandbox.api.app.firstsales.io/api/v1/organizations/{orgId}/workspaces/{wsId}/connectors/{connectorId}/settings \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "sendingConfig": {
    "dailyLimit": 260,
    "autoAdjust": true,
    "userDailySendLimit": 260
  },
  "syncSettings": {
    "twoWaySync": true,
    "historicalSyncWindowDays": 366
  },
  "resetBackfillCursor": true
}
'

const options = {
  method: 'PATCH',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    sendingConfig: {dailyLimit: 260, autoAdjust: true, userDailySendLimit: 260},
    syncSettings: {twoWaySync: true, historicalSyncWindowDays: 366},
    resetBackfillCursor: true
  })
};

fetch('https://sandbox.api.app.firstsales.io/api/v1/organizations/{orgId}/workspaces/{wsId}/connectors/{connectorId}/settings', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

{}

{
  "error": {
    "code": "<string>",
    "message": "<string>",
    "requestId": "<string>",
    "details": {}
  }
}