Write below query to find Index fragmentation.

SELECT ps.database_id, ps.OBJECT_ID,object_name(ps.object_id) AS [TableName],
ps.index_id, b.name,
ps.avg_fragmentation_in_percent
FROM sys.dm_db_index_physical_stats (DB_ID(), NULL, NULL, NULL, NULL) AS ps
INNER JOIN sys.indexes AS b ON ps.OBJECT_ID = b.OBJECT_ID
AND ps.index_id = b.index_id
WHERE ps.database_id = DB_ID() and b.name is not null
ORDER BY ps.avg_fragmentation_in_percent desc
GO

It will return TableName, IndexId , Name ,Index Fragmentation.

Now we can easily read the fragmentation and rebuild , reorganize indexes to get high performance.

If Index fragmentation is more than 20 it is totally disable for sql table. I think this is a good practice to get fragmentation percentage and rebuild , reorganize indexes.