I am definitely not an English teacher and am here to review my own English skills. Below is my input on your post: Do be sure to critically assess my input.
"Like" is a word that has moved from the grammatically incorrect to slang status, from slang status to grammar review, and now sits somewhere between acceptable because English is a living language (under constant change due to popular use) and grating. If this sentence is for an English assignment, you probably shouldn't use the word "like" in the way you did.
"adays" is an idiom and is spelled "a days" or spelled with a hyphen as in "a-days"; the first is probably more proper.
"Earlier people" - Do you mean "earlier-people" as in indigenous peoples or "Earlier, people" as in "people from an earlier era"; I suspect you meant the second. This said, now a days punctuation marks are discouraged when ever possible.
"used to" - I can't remember why you're not suppose to use "used to" but you might consider using "Earlier, people got married..."
You have used two different forms of "early" within the first nine words and to refer to two different conceptual entities. For the "age" concept, you might want to switch to some form of "young".
Put together, you might try something along the lines of:
Earlier, people got married at a younger age, like 16-18, ....
Earlier, people got married somewhere around the ages of 16 to 18, ...
Earlier, people married at younger ages, like 16-18, ....
Earlier, people married at a younger age, around 16-18, .....
"has got" is grammatically incorrect and should be "has gotten". I can't tell you why which is one of the reasons why I am here at this site.
I'm not sure that "age criteria" is the correct verbage. "Criteria" implies that a set of rules, laws, or some other check-list type of item is being met. You might replace it with "the general marriage age..."
Likewise, "expanded" would probably be better if replaced by "extended".
Earlier, people got married somewhere around the ages of 16 to 18, but now a days the general marriage age has been extended to between 28 and 30.
Earlier, people got married somewhere around the ages of 16 to 18, but now a days the general age has been extended; they are not getting married before the ages of 28 to 30.
(Personally, I like the semi-colon but it is no longer popular and often regarded as excess punctuation; another reason I've joined this site. I do believe that the semi-colon sentence is grammatically correct however, it does change tense at the "but", and then again at the semi-colon, which many instructors won't allow.)
Please check. "Earlier people used to get married at an early age like 16-18, but now adays age criteria has got expanded and the people do not marry before the age of 28-30" or "they are not getting married before the age of 28-30".
Student or Learner