The arrangement of electron pairs around the central atom is octahedral and shape is not octahedral can be identified with the help of presence of lone pair $(l p)$ of electrons and bond pair $(b p)$ of electrons associated with the central atom.
The structure of given species are:
(i) $SF _{6}$ Central atom sulphur has $6$ valence electrons,
which are bonded with $6 F$ -atoms,
thus have octahedral shape
(ii) XeF $_{6}$ Central atom, $Xe$ have $8$ valence electrons,
out of which $6$ are bonded with $6 F$-atoms and one $l p$ of electron is associated with $Xe$-atom.
Thus, has distorted octahedral shape.
$BrF_{5}$ Central atom $(Br)$ have $7 $ valence electrons,
out of which $5$ are bonded with $5F$-atoms and one $lp$ of electron is associated with $Br$-atom having square pyramidal shape.
$X e O _{2} F _{4}$ Central atom, $Xe$ have $8$ valence electrons,
out of which $4$ are bonded through $4$ -sigma $(\sigma)$ bonds with $4 F$ -atoms and two oxygen atoms each having one sigma $(\sigma)$ bond and one pi $(\pi)$ bond is associated with $Xe$-atom.
