How to combine multiple new meshes without instantiating?

Hello, I’m working on a game that uses a 3D tile system of sorts. For performance and utility reasons I need to combine many smaller pieces into one large mesh. These smaller chunks are instantiated procedurally and at runtime. I’ve looked at CombineInstance and MeshCombine classes, and while it’s helpful, I don’t think it’s fully what I’m looking for. I want a way to create or add to a current mesh without having to Instantiate the necessary gameObject. Is this possible?

If you don’t to do it procedurally, you can always use blender to combine and save meshes in positions you want as a single mesh.