It's impossible to send an octet-string not formatted as a display-string in both set and multiple varbind requests.
In my case I want to send a date formatted as date and time where 2024-09-04 13:21:35,1 translates to:
0x07 0xE8 0x09 0x04 0x0D 0x15 0x23 0x01
Entering such data as value in the value field does send the textual value instead of hex bytes.
But being octet-strings automatically parsed as displaystring (ASCII Strings) it's impossible to send such format of data.