Most cars since about the mid-00s and all cars since 2013 have isofix, so if your car is relatively modern then it's likely it has isofix attachments.
Whether a specific seat will be compatible is a different question. Do you have a particular seat in mind? Have you consulted the fit list for the car seat? This is usually attached to the seat when you buy it or you can check on the manufacturer's website if you are considering a seat to buy.
Many cars newer than 2013 will also have i-size compliant points in them, if your car has i-size positions then you can use any i-size car seat in that seat without consulting a fit list.
However i-size and fit lists don't always tell you if a fit will be comfortable e.g. allowing enough space in front for a tall passenger, allowing for a good angle for a rear facing seat. In order to get the best idea of how a car seat will fit, it's best to go to a stockist and have a test fit in the car before you buy.