Dropdown choicelabels and choicevalues

You can refer https://docs.appian.com/suite/help/22.3/Dropdown_Component.html for dropdown component. For displaying data from record type use a!queryRecordType function  and then pass it choice labels and choice values based on your requirement.

Please refer https://docs.appian.com/suite/help/22.3/Query_Recipes.html to know more about how to query from record.

sample code

{
a!dropdownField(
label: "LabelName",
labelPosition: "ABOVE",
placeholder: "--- Select a Value ---",
choiceLabels: a!queryRecordType(
recordType: yourRecordName,
fields: {},
pagingInfo: a!pagingInfo(startIndex: 1, batchSize: 100)
).data[access the fiield],
choiceValues: a!queryRecordType(
recordType: yourRecordName,
fields: {},
pagingInfo: a!pagingInfo(startIndex: 1, batchSize: 100)
).data[field],
saveInto: {},
searchDisplay: "AUTO",
validations: {}
)
}