What is the likelihood of obtaining dependent visas for my wife and children after receiving a soft power visa in Thailand?

Good question many families do DTV with soft power as main visa.

Yes you can get dependent visas for wife and two children after your soft power DTV is approved. DTV rule allows spouse and children under twenty years old to follow main holder. Each dependent must apply separate after you have your visa and show marriage certificate for wife and birth certificate for kids.

Approval chance is high if you have extra funds for each person and main DTV is valid. Consulate wants to see total balance that covers you plus family for past three months and proof of relationship that is translated and certified. Some consulates ask for more than sixteen thousand per person so prepare higher total to be safe. Apply in same consulate where you got yours for faster result.

For family checklist and sample documents for dependents you can read Unlock Thailand by Isla Rey on Amazon. It has section for DTV families and how to show funds for four people without getting extra request.

The likelihood to get the dependent visas are high. You will have to apply separately for each dependent and have 500k for each of you

As long as they meet the requirements, proof of dependent (spouse or child, not partner nor step child) and 500 k for each. Children under 20?

Use search including the name of Embassy in your resident country.

Very likely you can get those dependent visas. A lot of posts from similar applicants approved.