Screenshot of the Timelines settings where the default value for "Truncate long messages is set to zero", this option means no limits on messages.
https://storage.gra.cloud.ovh.net/v1/AUTH_91eb37814936490c95da7b85993cc2ff/tootfedilabapp/media_attachments/files/113/760/888/680/460/884/original/eb58444d32235b8f.png