Yes, you can make voluntary contributions to the Central Provident Fund (CPF) to build up your retirement savings. These contributions can also be used for your housing and health care needs.
Suggested Readings
Is there any limit or quota on the number of Employment Pass (EP) applications a Company can make?
How do I check my Central Provident Fund (CPF) Statement of Account?
If I should pass on, can I make a Nomination for someone to be a beneficiary of my Central Provident Fund (CPF) savings?
Who does Central Provident Fund (CPF) apply for?