Of course he sounds like he believes that there was electoral fraud. Any con artist who is any good at their trade will tell you whatever it takes to get you to fall for whatever they are selling. Trump has a consistent record of these sorts of things. Have you ever heard him, even once accept blame for anything at all? It is always someone else's fault.
In the call he threatened the officials involved with the election and demanded that they "find" enough votes to put him ahead. We also know that the senior Justice Department official in Atlanta (a Trump appointee) was forced out for not doing enough on Trump's behalf. Many of the Republican leaders who have gone along with his claims are doing so on the basis of a cynical calculation that it will be to their benefit. Others, perhaps because they fear for the safety of themselves and their families.