Rebuild all indexes for all tables and all databases

Maintain database indexes

You can just create script or run right now the reindex.
Verify the configuration to filter databases or to change the FILLFACTOR.

PRINT '-- ***************************************** --'
PRINT '-- Reindex all tables'
PRINT '-- on selected databases'
PRINT '-- ***************************************** --'
PRINT '--'
PRINT '/*'
PRINT @@servername;
PRINT Getdate();
PRINT '*/'
SET NOCOUNT ON;

-- CONFIGURATION
DECLARE @runScriptRightNow INT = 0;
DECLARE @fillfactor AS NVARCHAR(10) = '99' -- occuped% -- https://docs.microsoft.com/en-us/sql/relational-databases/indexes/specify-fill-factor-for-an-index
BEGIN TRY DROP TABLE #dbs; END TRY BEGIN CATCH END CATCH;
SELECT [name] INTO #dbs FROM sys.databases
WHERE database_id > 4
AND name NOT IN ('MyDatabaseNoReindex')
ORDER BY [name]

-- CONFIGURATION

USE [MASTER];

DECLARE @dbname nvarchar(200);
DECLARE @sql NVARCHAR(MAX);
DECLARE @ToKill AS NVARCHAR(MAX);

DECLARE @templateSelectTable AS NVARCHAR(MAX) = 'SELECT ''['' + table_catalog + ''].['' + table_schema + ''].['' + table_name + '']'' as tableName FROM [$(dbname)].INFORMATION_SCHEMA.TABLES WHERE table_type = ''BASE TABLE''' 
DECLARE @templateReindex AS NVARCHAR(MAX) ='ALTER INDEX ALL ON $(tablename) REBUILD WITH (FILLFACTOR = $(fillfactor));'
SET @templateReindex = REPLACE(@templateReindex,'$(fillfactor)',@fillfactor)
 
DECLARE @table AS table (TableName nvarchar(256))
DECLARE @script AS table (Idx int identity,SqlScript nvarchar(max))
DECLARE @Idx int;
DECLARE @SqlScript nvarchar(max)
WHILE (EXISTS(SELECT * FROM #dbs))
BEGIN

    SELECT TOP 1 @dbname = name FROM #dbs;
    DELETE FROM #dbs     WHERE name = @dbname;

 SET @sql = REPLACE(@templateSelectTable,'$(dbname)',@dbname);
 DELETE FROM @table;
 INSERT INTO @table (TableName)
 EXEC(@sql)

 INSERT INTO  @script(SqlScript)
 select REPLACE(@templateReindex,'$(tablename)',TableName) from  @table;

 WHILE (EXISTS(SELECT * FROM @script))
 BEGIN
  SELECT TOP 1 @Idx = Idx, @SqlScript = SqlScript FROM @script t;
  DELETE FROM @script WHERE Idx = @Idx;
  
  IF (@runScriptRightNow = 1)
  BEGIN
   RAISERROR (@SqlScript, 10, 1) WITH NOWAIT;
   EXEC (@SqlScript);
  END
  ELSE
  PRINT @SqlScript
 END

END

Same code with safe mode and try again

GO
PRINT '-- ***************************************** --'
PRINT '-- Reindex all tables with safe mode'
PRINT '-- on selected databases'
PRINT '-- ***************************************** --'
PRINT '--'
PRINT '-- ' +@@servername;
PRINT '-- ' +cast(Getdate() as nvarchar(100));
SET NOCOUNT ON;

-- CONFIGURATION
DECLARE @runScriptRightNow INT = 1;
DECLARE @fillfactor AS NVARCHAR(10) = '98' -- occuped% -- https://docs.microsoft.com/en-us/sql/relational-databases/indexes/specify-fill-factor-for-an-index

BEGIN TRY DROP TABLE #dbs; END TRY BEGIN CATCH END CATCH;
SELECT [name] INTO #dbs FROM sys.databases
WHERE database_id > 4
AND name   IN ('MyDatabaseNoReindex')
ORDER BY [name]

-- CONFIGURATION$(ESCAPE_NONE(dbname))

USE [MASTER];

DECLARE @dbname nvarchar(200);
DECLARE @sql NVARCHAR(MAX);
DECLARE @ToKill AS NVARCHAR(MAX);

DECLARE @templateSelectTable AS NVARCHAR(MAX) = 'SELECT ''['' + table_catalog + ''].['' + table_schema + ''].['' + table_name + '']'' as tableName FROM [[#dbname]].INFORMATION_SCHEMA.TABLES WHERE table_type = ''BASE TABLE'''  
DECLARE @templateReindex AS NVARCHAR(MAX) ='
DECLARE @tryAgain INT = 2;
WHILE (@tryAgain>0)
BEGIN
    BEGIN TRY
        PRINT ''-- REINDEX Table  : [#tablename]'';
        ALTER INDEX ALL ON [#tablename] REBUILD WITH (FILLFACTOR = [#fillfactor]));
    END TRY
    BEGIN CATCH
        SET @tryAgain = @tryAgain - 1;
        WAITFOR DELAY ''00:00:10'';
        CONTINUE;
    END CATCH
    BREAK;
END;
'
SET @templateReindex = REPLACE(@templateReindex,'[#fillfactor])',@fillfactor)
 
DECLARE @table AS table (TableName nvarchar(256))
DECLARE @script AS table (Idx int identity,SqlScript nvarchar(max))
DECLARE @Idx int;
DECLARE @SqlScript nvarchar(max)
WHILE (EXISTS(SELECT * FROM #dbs))
BEGIN

    SELECT TOP 1 @dbname = name FROM #dbs;
    DELETE FROM #dbs     WHERE name = @dbname;

    SET @sql = REPLACE(@templateSelectTable,'[#dbname]',@dbname);
    DELETE FROM @table;
    INSERT INTO @table (TableName)
    EXEC(@sql)

    INSERT INTO  @script(SqlScript)
    select REPLACE(@templateReindex,'[#tablename]',TableName) from  @table;

    WHILE (EXISTS(SELECT * FROM @script))
    BEGIN
        SELECT TOP 1 @Idx = Idx, @SqlScript = SqlScript FROM @script t;
        DELETE FROM @script WHERE Idx = @Idx;
        
        IF (@runScriptRightNow = 1)
        BEGIN
            RAISERROR (@SqlScript, 10, 1) WITH NOWAIT;
            RAISERROR ('GO', 10, 1) WITH NOWAIT;
            EXEC (@SqlScript);
        END
        ELSE
        PRINT @SqlScript
    END

END
GO

Sources :

https://docs.microsoft.com/en-us/sql/relational-databases/indexes/specify-fill-factor-for-an-index
https://www.mssqltips.com/sqlservertip/1367/sql-server-script-to-rebuild-all-indexes-for-all-tables-and-all-databases/