I set this option, but it doesn't work.
My own expirience says: if you logout after changed DPI-Settings (different to "Ease of Access>Make text bigger") to a hight percentage (at Tablet to 150% for example), the login-Screen-Text is bigger.
Annoying, that some users need the Tablet-DPI-Setting with 100% scaling.
So i think, the only way is to rewrite my application, that needs this 100% DPI-scaling, into 150% DPI-scaling requirement.
Much thank to your answer, Eleven.