My only thought on this is that in the ending in which Ciri becomes Empress, Geralt has done absolutely nothing that would force her to take on that role. Sure he brought her father, but he didn't force her to go, she asks him if he thinks she should, he says "I do", and she decides to accept his advice. She leaves afterwards of her own free will so it isn't like Emyhr forced her to stay in Vizima and take the job, she left pretty pissed and with nobody trying to stop her. At that point all that happened was that she heard Emhyr's proposition for her future (that he thought she should be Empress), and was allowed to leave and make her own decision. At the very end, she never even told Geralt she accepted the job, she did it behind his back, he finds out last minute that this was what she'd decided to do leading the Nilfgaardians to show up at White Orchard. They see the Nilfgaardians long before they see Geralt and Ciri, and Geralt asks her about it. She says that she approached them and took the job, not that they are forcing her. He asks her if she's sure about this as he'll have her back if she has changed her mind and wishes to either fight or flee. She says she is sure and that this is what she wants to do.
So with the Empress Ciri ending, she had multiple points during which she could have not approached Nilfgard, changed her mind, fled, and made really any decision she so wished about her own future and where it would lead. She is the goddamn Lady of Time and Space and nobody can force her to do anything she doesn't want to, especially with Geralt and Yenn backing her up, all Geralt did to get the Empress ending was give her the OPPORTUNITY to either accept or decline the Empress-ship, it was 100% her choice in the end to accept. By getting the Empress ending she had more freedom than any of the others to do whatever she wished, she could have traveled the world with Geralt, gone to other worlds alone, or become Empress, in the end she made the decision for herself on what she wanted.
Plus she can still travel the world if she wants and visit whoever she likes. The only thing that would stop a ruler in those times from being well traveled is that travel took a long time and you couldn't just abandon your people for months on end to traverse the continent to visit someone or see something. For example, look how much rulers travel now that airlines exist and its doesn't take months to reach their destinations. However, Ciri isn't limited by time when it comes to travel. There is literally nothing to stop her from teleporting away for a weekend to wherever she wants. Hell, she could even return back to the palace each day for an hour to make sure nothing has happened while she was away and that she isn't needed while she was away visiting.