Scrum is a framework for products. A Scrum Team should be a self-organizing, cross-functional team of professionals that is dedicated to working on a single product.
If your projects are separate products, then you should have multiple Scrum Teams. Each Scrum Team would have a Product Owner, Developers, and a Scrum Master. They would be run independently, with their own Product Goals, Product Backlog, Sprints, Sprint Backlogs, and events. You would not need to apply scaling frameworks, since each Scrum Team would be a small team.
However, if the projects are facets of a single product, then you may be able to apply some scaling frameworks. Examples of these scaling frameworks include Nexus and LeSS. However, scaling frameworks should typically be a last resort. A Product Owner, a Scrum Master, and 10-12 Developers is probably on the larger size for a Scrum Team, but it could still be effective. Having a team collaborate and share a focus on a single Product Goal and Sprint Goal would likely be more effective than splitting the focus into 3 disjoint efforts.
Only after you determine the correct organizational structure can you configure Jira (or any other tools). Tools should be configured to support the people and the way of working.