Yes, if he is your step son, then some colleges may require financial information from his other biological parent as well.
https://profile.collegeboard.org/profile/ppi/participatingInstitutions.aspx lists colleges that use CSS Profile in addition to FAFSA. Column 4 indicates whether the CSS non-custodial parent Profile is used. Beware that there are a few schools that require non-custodial parent information but not on CSS Profile (e.g. Oberlin; Princeton also, but not if the custodial parent is (re)married). If the non-custodial parent is uncooperative with financial aid forms or has significant income/wealth but will not pay, that can make these colleges unaffordable on need-based financial aid.
When running net price calculators, check the college’s web site whether non-custodial parent information is required. If so, include the finances for his other biological parent as well as those of your household to avoid getting an unrealistically optimistic estimate based only on your household finances (but net price calculators are often less accurate in this case even if you do that).