Install the corresponding driver from the AUR
yay -S brother-dcpt300
Scanner drivers. brscan4
is required for the DCP-T300. Look at this link other scanners.
yay -S brscan4
To enable scanning using the printer hardware buttons
yay -S brscan-skey
Install a frontend to scan, print, create pdfs from images, etc
sudo pacman -S gscan2pdf
Reboot/Logout 🎉