When using the 'Create new scratch org' screen the following features are not available in the 'Scratch Org features' list

OmnistudioMetadata
OmnistudioRuntime
OmnistudioDesigner

These are available features according to the Salesforce documentation

https://developer.salesforce.com/docs/atlas.en-us.sfdx_dev.meta/sfdx_dev/sfdx_dev_scratch_orgs_def_file_config_values.htm#so_omnistudiodesigner