Plaster thickness is everything re whether this will work.
16mm hard plaster, end-expansion plug, tight hole - whilst the 19mm screw does not reach the brick it may grip enough for shear and light pull-out resistance.
3mm hard plaster, 20mm rubbish sand-cement render, MID-expansion Fischer SX6 30mm plug - whilst a 25mm screw sounds longer, it causes mid-expansion of the plug and very weak pull-out resistance. I know, because a test-pull of a radiator fitted thus removed the plugs from the holes with screws still snugged tight up to the bracket! Now had I gone with a b@st@rd 40mm screw and things are very different, the 4- way expansion plugs are very strong. Instead I have a wall to (still) repair which unobtainium wallpaper at unobtainium price in any case.
Personally a 3/4" #8 is only good for holding a backbox still in an SX6-30 whilst the plaster goes off.
I think the old "torx-style-fibre-rawlplug" are more tolerant of short screw depth, the modern polythene type rely on interference fit without much grip, the nylon 4-way mid-expansion Fischer grip well if you use a long enough screw and a tight hole which is critical otherwise they will pull out.