Snipe-IT custom fields can be synced, displayed and edited in the asset details view of your Jira issues.
Navigate to the Snipe-IT for Jira configuration page: Jira settings > Apps > Snipe-IT for Jira > Configuration
In the menu item “Show custom fields in asset details” select in the dropdown the custom fields that should be displayed
Select “Allow editing Snipe-IT assets from Jira” to enable editing assets within Jira. You can then select which fields can be edited via the dropdown “Allow editing of fields”.