The following instructions have been used to startup chrome from https://smarthomepursuits.com/open-website-on-startup-with-raspberry-pi-os/
On your pi you can edit the file ~/.config/lxsession/LXDE-pi/autostart using the following command in terminal
sudo leafpad ~/.config/lxsession/LXDE-pi/autostart
.
@lxpanel --profile LXDE-pi @pcmanfm --desktop --profile LXDE-pi @xscreensaver -no-splash point-rpi #kiosk mode modifications @xset s off @xset -dpms @xset s noblank @chromium-browser --noerrors --disable-session-crashed-bubble --disable-infobars --start-fullscreen --incognito https://www.website.co.uk/slideshow/