My 4 year old have problem speaking /pronouncing R and l

A. R is a really tricky alphabet a lot of times kids can take about 4 to 6 years of age or seven years of age to pronounce it correctly which is not a problem where when you talk about I he is a very simple thing to be seen but if your child is facing problem with the pronunciation rest the speech is fine I don’t think so need to consult a doctor just a matter of time the more you practise the child is going to learn better with time