That's correct. Unexplained Wealth Orders target amounts in excess of £50 000 (usually far in excess, they've been used four times so far, with total targets of 143
million pounds).
The UWO must target an individual who is either: Politically exposed (e.g. (ex)leaders and senior officials of a country and their families) or Reasonably Believed to be involved in Serious Crime (e.g. bank robbers) and whose wealth lacks an apparent explanation. If the target either can't or won't explain their wealth it may be seized.
UWOs are supposed to be reformed to make them work even when you've paid lawyers to make the apparent ownership very opaque. Right now if you're benefiting from an opaque "trust" arrangement maybe spanning several countries it may be impossible to show how that wealth is really "yours" legally, without the co-operation you would have been required to show as part of the UWO.
In practice it often happens, as I understand it, that the UWO target decides the best way out is to just hand over the wealth, because the real answer to "Why do you have this wealth?" is "I did a bunch of crimes" and that is a confession of crime, for which you might do prison time, and either they don't trust lawyers or the lawyers they hired couldn't come up with another story that would hold water.
Sadly the current (Tory) and former (Tory, Tory, and Tory back many years now) UK governments have been much better at talking up their commitment to transparency than at actually taking any steps to prevent the UK (and especially London) functioning as a laundromat and dormitory for crooks to wash their dirty money and sleep comfortably knowing the people they stole from can't reach them...