Adopt long cycles, spend most of it rewriting, cram every feature into the last couple of weeks so you have something to show for in the PI Planning. Blame subpar performance on lack of staff. You will luckily be awarded with more workforce you can employ in rewriting code. Repeat until done or fired.
It depends on the organization. Most teams in most organizations have enough freedom (and rightly so) to do some kind of cleanup work, improvements, refactorings. When the development team is unsatisfied with the state of the application and they feel they will not get buy in for rewrite (and usually rightly so...) they might decide they will rebrand it as internal improvements/cleanup/refactoring. Have seen it many times.
Developers are autonomous, they can decide what to work on and start a rewrite without approval. Call it a cleanup/refactoring if management doesn't like rewrites.