How to make default Landing Page as Setup page in Salesforce

To make the default landing page as setup page, go to the 'Advanced User Details' of the user and enable the 'Make Setup My Default Landing Page' permission.

How to get Default Record Type Id of object using apex in salesforce

In this example, I am getting Account object default record type Id

Example

Schema.DescribeSObjectResult describeResult = Account.getsObjectType().getDescribe();
List<Schema.RecordTypeInfo> rtInfos = describeResult.getRecordTypeInfos();
for(Schema.RecordTypeInfo rtInfo : rtInfos) {
    
    if(rtInfo.isDefaultRecordTypeMapping()) {       
        System.debug('Default Record Type Id ====> '+rtInfo.getRecordTypeId());
    }
}  

Result