In 2021, the primary tools for viewing and managing schematics were focused on in-game mods and browser-based viewers, as older standalone programs like MCEdit had largely become outdated madelinemiller.dev Leading Schematic Tools in 2021 Litematica

files in 3D. It was a go-to in 2021 for users who wanted to quickly check the contents of a file without launching the game. Amulet Editor

If you want, I can:

How to Use & Create schematics Minecraft World Edit Guide (7)

While known for skins, NameMc added a robust schematic viewer recently.