SUMMARY
There is currently no way to configure the distance (in pixels or else) from the screen edge required to trigger Quick Tiling (the feature where windows resize to half or quarter of the screen when dragged to edges or corners).
A setting to control this distance would improve usability and accessibility, especially between two screens (where you're not blocked because it's a false edge).

STEPS TO REPRODUCE
1. Grab a window and drag it toward the side or corner of the screen
2. Observe when the "Quick Tiling" preview appears (indicating the window will tile to half or quarter of the screen)
3. Try to adjust the distance needed to trigger this behavior — no setting exists in System Settings or kwinrc

OBSERVED RESULT
The Quick Tiling behavior triggers at a fixed distance (approx. 10–15 pixels from screen edge)
This distance is not configurable via GUI or in config files

EXPECTED RESULT
A setting could be available (in System Settings or kwinrc) to configure the Quick Tiling activation distance
Example: TriggerDistance=10 under [Tiling]
This would allow users to fine-tune how close to the edge they need to drag to trigger tiling.
Also an additional setting to scale this distance by a multiplier when the edge is between two screens (I don't know if it's easy to determine if an edge is next to another screen edge). Example : TriggerDistanceMultiplierForEdgesNextToAnotherScreen=10 under [Tiling]

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: KDE Neon (under Ubuntu)
KDE Plasma Version: 6.4.5
KDE Frameworks Version: 6.18.0
Qt Version: 6.9.2

ADDITIONAL INFORMATION
I love the work you've all put into KDE Plasma ! KDE Plasma completely exceeded my expectations — the overall quality is outstanding, Windows is far away now :)