It isn’t possible to resize a file system without adding more inodes: that would require changing the number of bytes per inode (as a ratio of the storage size over the number of inodes), and that’s not possible in Ext4. As explained in `man mke2fs`:

> `-i bytes-per-inode`<br>
              Specify the bytes/inode ratio.  `mke2fs` creates an inode for
              every _bytes-per-inode_ bytes of space on the disk.  The
              larger the _bytes-per-inode_ ratio, the fewer inodes will be
              created.  This value generally shouldn't be smaller than
              the blocksize of the file system, since in that case more
              inodes would be made than can ever be used.  Be warned that
              it is not possible to change this ratio on a file system
              after it is created, so be careful deciding the correct
              value for this parameter.  Note that resizing a file system
              changes the number of inodes to maintain this ratio.

Instead of resizing the existing volume, you could create a new volume using the available free space, with a much lower number of inodes, then move the data across and resize the new volume. You might have to do this in several steps if the free space isn’t large enough to store all the data currently on the volume.