SUMMARY
If I tell Dolphin to sort a single folder by a different option (creating a .directory file), the file-open dialog still uses global sort options.

STEPS TO REPRODUCE
1. Open Dolphin Preferences. In the General pane, Behavior tab, select "View: Remember display style for each folder". (If this step is omitted, the expected result is different but observed is unchanged.)
2. Open a folder in Dolphin. Click the sorting header (which changes the per-folder sort options, saving it in the .directory file)
3. In a KDE app, open an Open dialog and navigate to the same folder.

OBSERVED RESULT
The sorting option persists across folders, and is remembered when you close the dialog and open a new one in the same or different folder. It is not tied to either the global or per-folder sorting options set by Dolphin.

EXPECTED RESULT
The file-open dialog respects per-folder (and global) sorting options set in Dolphin. If per-folder sorting is enabled, changing the dialog's sort options in a folder creates a .directory file, which also changes the sorting in Dolphin (as well as file dialogs). If per-folder sorting is disabled, changing the dialog's sort options may reconfigure Dolphin's sort options as well (unsure if that's a good idea).

SOFTWARE/OS VERSIONS
Operating System: Garuda Linux
KDE Plasma Version: 5.21.1
KDE Frameworks Version: 5.79.0
Qt Version: 5.15.2
Kernel Version: 5.11.1-127-tkg-bmq
OS Type: 64-bit
Graphics Platform: X11
Processors: 4 × Intel® Core™ i5-6200U CPU @ 2.30GHz
Memory: 7.6 GiB of RAM
Graphics Processor: Mesa Intel® HD Graphics 520

ADDITIONAL INFORMATION
The behavior I'm requesting mimics how Windows handles per-folder sort in Windows Explorer and file-open dialogs.