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.