Up until the age around the age 5-6, children are learning how to produce sounds and will have some speech sound errors.
A good guide for when to check in is asking people around you how much they understand of your toddler’s speech. By the age of 2, an unfamiliar listener should understand around 50% of what your toddler says. By the age of 3, this is about 75%, and by the age of 4 it is at about 95-100%. If you feel like you are often needing to translate for your little one and they are not understood by others most of the time, it might be good to check in with a speech pathologist!