A child restraint system fastened using a seatbelt (universal category) can be fitted in any seat with a seat belt with 3 anchor points.
An ISOFIX child restraint system with top tether upper fastening (universal category) can be fitted in any vehicle seat with ISOFIX anchor points and a top tether upper anchoring point. If the device is ISOFIX with a support leg (semi-universal category) you should consult the product's list of vehicles to make sure of the compatible vehicles and seats.
When the child restraint device is facing backwards, it can only be installed in seats with the front airbag and providing that the airbag has been de-activated.
Refer to the instruction manual of your vehicle to find out the compatibility of the vehicle's seats with the various child restraint systems.