If US citizen filing an I-130 for parents, can my sibling come under the same petition?

Generally, a U.S. citizen age 21 or older may petition for a parent to obtain immigration benefits in the Immediate Relative visa category. Doing so, however, would not authorize adding a 23-year old brother as a "derivative beneficiary" even if the brother is dependent upon the parent, and so other avenues should be explored for the brother. That might include, as you suggested, having a parent file for your brother after the parent obtains immigration status. It also might include, if applicable, an independent application for the brother based on employment offer from an employer qualified and willing to sponsor him, or an application in the F4 visa category that you could file directly for your brother (but be aware of a very long backlog for visas in that category). It would be wise for you and your parents to consult with an immigration attorney about legal representation in the often quite complex application process to achieve their goals; at that time an immigration attorney also could explore potential eligibilities, options and strategies for your brother.