Does anyone know if a 2019 Octavia Estate has the ability to power a fridge/charge a leisre battery while travelling and if not what kit is required ?

That should be a standard function of the 13 pin (or 12s) socket fitted with the towbar.

See pins 9 & 10 of the 13 pin socket.

The fridge should be wired to pin 10 which is supposed to be ignition switched.

Edited 17 August, 202517 Aug by PetrolDave

You could buy a 12 v Dc -dc charger like this one which lots of serious vanners use

https://www.edisons.com.au/ctek-smartpass-120s-power-management-system-120a-with-battery-starter-function-for-starter-and-service-batteries-smart-alternator-compatible?gad_source=1&gad_campaignid=17425415009&gclid=Cj0KCQjw-4XFBhCBARIsAAdNOkt-R2RT7pnXFQwcU8xf8hv-9lYqpHgL1ymErfzw_TcDWLIWPn4EprEaAqOeEALw_wcB