He claims any ceasefire where he spoke to at least one leader or publicly said they need to stop
For example, he claimed he got peace between India and Pakistan. They regularly have border disputes that never, fortunately, get very big.
He claims he ended a long war between Cambodia and Thailand. They don't credit him with this. In the Democratic republic of Congo, the US had been working for years to resolve the violence. I'm not sure that there is peace now or that anyone from the Trump administration should get credit.
Any US SoS is involved in helping with disputes and many ceasefire are broken quickly. How many times were there ceasefires in Syria or Sudan ... only for violence to continue. A ceasefire is better than fighting, but it is usually the first step towards a real resolution to the underlying problem.
When you look at either Israel/Gaza or Ukraine/Russia it is possible he has made a future resolution harder.