Currently you cannot create automation rules that have logic for multiple projects even if you a project admin with access to manage automation rules in those projects.

The functionality exists but only for the Jira Admin role which is restricted at most companies.

Even if you ask a Jira Admin to update a rule to have multiple project scope, the rule becomes read-only for project admins so they cannot edit it or event disable it.

From a quick search, I came across a few other examples of where people have looked for this functionality:

1. https://community.atlassian.com/t5/Jira-questions/Creating-a-automation-rule-that-can-be-accessed-across-multiple/qaq-p/2563241
2. https://community.atlassian.com/t5/Jira-questions/One-automation-multiple-projects/qaq-p/2291755
3. https://community.atlassian.com/t5/Jira-Service-Management/Automation-across-two-projects/qaq-p/2195469
4. https://community.atlassian.com/t5/Jira-questions/Can-I-use-an-automation-rule-across-multiple-projects/qaq-p/2607908