Are elders required to be old? Yes, but how old? In the Scriptures there is no defined age to be an elder, but in 1 Timothy 3:4 and Titus 1:6, Paul gives rules to the office of bishop, that will allow us to determine the age of an elder.
One that ruleth well his own house, having his children in subjection with all gravity; [1 Timothy 3:4]
If any be blameless, the husband of one wife, having faithful children not accused of riot or unruly. [Titus 1:6]
In these verses, it is indicated that he must be a man old enough to have raised children and that they (the children) could demonstrate their good testimony and obedience to authority, therefore, they should be mature.
Thus, the aspiring presbyter had to show that he had raised decent children, obedient to the faith and to their father. So, it can be deduced that he was a man not less than 45 years old, considering an adult from the age of 20 (Exodus 30:14; 38:26; Numbers 1:3, 20; 32:11)