Since you can not create expense accounts, (categories) in QBSE
and since, though it advertises itself as schedule C compliant, it ignores COGS (line 4 and part III)

all you can do is use the supplies category to post the purchase costs of what you sell or use to make something to […]

Resolution for 'C compliant issue: 'How can I track cost of goods sold in QBSE?' available: Yes.

The C compliant issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the C compliant issue yourself by looking for a resolution described in the article. If it is a complex C compliant issue or you are unable to solve the issue, you may contact us by clicking here or by using other C compliant support options.

For more information about resolving issues related to C compliant in Quickbooks/QBO or to get support for the issue 'How can I track cost of goods sold in QBSE?', click the link below: