Converting from the legacy format to the modern format is a necessary step for players importing older creations into modern Minecraft instances.
In the vast world of Minecraft build automation and schematic-based construction, two mods stand head and shoulders above the rest: (known for its .schematic file format, often called "Schematic files") and Litematica (the go-to Fabric mod for material lists, easy placement, and ghost-block rendering). schematic file to litematica converter link