You can make Qt look however you want. The point is that it will give you native UI by default (for the most part and excluding QML)
That native UI will be faster than Electron and most other retained UI toolkits and will be just as capable of creating whatever your subjective view of “modern UI” is.
That native UI will be faster than Electron and most other retained UI toolkits and will be just as capable of creating whatever your subjective view of “modern UI” is.