no- not in the US. The president can not change any laws at all. Only Congress can change the law . (The Supreme Court can nullify a law by ruling it to be in violation of the US Constitution.) The president can ask Congress to change a law and can campaign for congressional candidates who promise to repeal certain laws.
no
The outgoing president is still president until the incoming president takes the oath of office.
Because they liked the current president and wanted the terms to change so the president can be in office longer.
Nothing much. The outgoing president remains president until the new one takes the oath of office.
He appointed a chief justice the night before Jefferson took the oath of office.
The president elect is someone who has been elected president but who has not yet been sworn in, or officially taken office. It is still occupied by the current outgoing president. The President still has the job of being president until the president-elect has been sworn in.
When the current president dies. Also if the current president resigns from office. Also if the president is impeachedAdded: . . . or becomes too ill or incapacitated to carry out his duties,
A national disaster does not change when the president-elect gets sworn in to office. However, it might change the location of where he is sworn in to office.
The President leaves when his term(s) expires. After he leaves office, he retire whenever he likes. He gets his presidential pension immediately after leaving office under current policy which Congress can change at any time.
Joe Biden
Most recent (and current) US President is Barrack Obama.