Can i apply VOA in Kunming from Singapore

No, unfortunately, there is no VOA for Kunming.

You as a Singaporean citizen can rely on 144 hour visa free transit, but you should create your flight itinerary that your visit to Kunming appears to be as a transit. In other words, if you fly:

Singapore - Kunming - Hong Kong - Singapore

or

Singapore - Hong Kong - Kunming - Macau

or

Singapore - Kunming - Kuala Lumpur

You will be eligible for 144 hour visa free transit and you will not need a visa.

So, the only detail you need to have in mind is that immediate points before and after Kunming, have to be in two different geographical entities or in other words, countries or Chinese provinces of Hong Kong, Taiwan and Macau that act as third countries in this regard.