No. If your employer's CHOICE offer is considered affordable under IRS rules (generally, if your lowest-cost self-only coverage doesn't exceed 10.22% of your household income in 2027), you and your dependents are ineligible for premium tax credits on the ACA marketplace—even if you decline the CHOICE.
Your employer provides an affordability determination as part of your CHOICE offer. If you have questions about your specific situation, reach out to support or consult a tax professional.