I found the answer in this thread: [OH3] Add metadata to Items via configuration files
This is what worked for me.
Number ShellyRGBW2AlwinRegalhinten_Schema "Schema" <text> (alwin_room, tasmota_rgb_scheme) ["Control", "ColorTemperature"] {
channel="mqtt:topic:BigmacBroker:shelly_rgbw2_alwin_shelf_back:Scheme",
stateDescription=""[
options="1=Static, 2=Cycle Up, 3=Cycle down"
]
}