When Trump opens his mouth, he's likely to be lying most of the time. Same goes for his cabinet and same goes for his family - like Ivanka's crocodile tears about the "viciousness" she didn't expect
.
They aren't lying with the expectation they'll convince anyone of "their truths" though, and that's significant. Trump, everyone in his administration, all the GOP legislators and Trump's children know there is ample, credible evidence out there to show that things they say are lies. Ivanka Trump is familiar with her father's Tweet stream, and long track record of brutality. In the video, cabinet members one after the other were lying through their teeth about accomplishments to win favour with their leader. Republican legislators lie their asses off about "Trumpcare" because frankly, they don't give a shit about the impact. Those who'll be affected most either a.) don't vote Republican, so who cares what happens to them or b.) will vote Republican even if the GOP murders their firstborn, so still, not worth worrying about.
They lie to show publicly that they CAN lie, and there's fuck all Americans or anyone else can do about it.
That is the purpose of the lying, whether it's soft and sweet "wounded" Ivanka or the arrogant fabrications of her father. It's to show their nigh on absolute power. If Trump makes good on his threats to sack the special prosecutor, and there's no opposition from within his administration or GOP members of congress (hint: there won't be,) it's another firm step towards undermining the republic. Authoritarian kleptocracy marches on.