No. Subtitles are visible only when played via USB mode or card reader on a player compatible with SRT subtitles. Subtitles are not visible on-camera or streaming playback from camera.
Playing directly on phone
Some mobile devices have SRT subtitle compatible players. You may try inserting the memory card in the mobile device or phone, or downloading both the MP4 and SRT files to the phone from the camera over Wi-Fi.
Advanced: Download via camera’s web client
With phone connected to (Her04) camera over Wi-Fi, open a web browser and enter address “10.5.5.9/videos” You may then select “DCIM” folder and the subfolder containing the desired video. Download (not open) the video MP4 and SRT files to the phone (long press or similar action to select download).