Can the settlement companies negotiate to lower the debt amount more?

When you take help of a settlement company, they actually contact the creditors and negotiate with them to reduce the payoff amount for settlement.
If you want to do it on your own, the month you face difficulty to make the monthly payments, you can contact the creditors and request for an alternative payment plan.
If you take help of a settlement company, they will offer complete professional guidance.

I don't understand your question.

Settlement companies know the industry trends, laws, and strategies well. Thy can negotiate hard and lower your debt amount well.

Debt settlement companies can negotiate with your creditors and lower your total debt amount. They can also help you make a monthly debt payoff plan to settle the debts easily. It's not like that creditors always happily agree to reduce your debts. It takes a lot of hard work and negotiation skill to make the deal possible.