Those multi stage multi use seats (newborn-7 years rear facing to harness to booster type ones) are not great, by trying to do everything they sacrifice in more than one area. You'd be best off with a long lasting erf seat with a high weight and height limit if he's on higher centiles. Do you know the centiles he's on?
He’s 68th for weight and 92nd for length
@Vicky definitely a 36kg seat then from the list Kiera posted 😊
For a tall baby/child Axkid miniki4, Axkid Movekid, Besafe Stretch. Axkid won’t be suitable until closer to a year old but the Besafe could be used quite soon, we used ours from 7-8 months and it would have fit earlier than that. The grow with me seats have a low harness limit, your child will outgrow that by 3 years old and you’ll need one of the above seats at that point. All stage seats are also are not great HBBs
What centiles is baby following for both height and weight?xx