Everything depends on the type of child restraint system. There are currently seats on the market that can be placed in either direction. The manufacturer may indicate that the child can travel in a rear-facing position up to a certain height and weight at which point the CRS can be positioned to face forward, although, as mentioned, this all depends on the type of seat. To be absolutely sure it is best to check the manufacturer’s manual.
In any case, it is advisable to get the child used to facing the rear since this is the safest position for them. Rear-facing child car seats offer better protection for the head, neck and spine, which are some of the most vulnerable parts of the body, particularly when it comes to young children.