You can prevent the Jira issue from transition to the next state if not all Smart Checklist items are checked. That's done by validating the
RequiresSmart Checklist Progress Custom Field→ "Smart Checklist Progress" Custom Field set up
☝🏼 NOTE: Not available in Next-Gen projects. Workflow customization isn't available yet for Next-Gen projects. As of now, it is on the longer-term roadmap of the Atlassian team. Therefore, transition validators are not available either.
Set up Validator
Go to Project Settings → Workflows
Choose the Workflow you want to add validation to and click Edit:
3.1. Choose transition and click on the Validators link:
3.2. Add Validator: