Identify duplicate leads salesforce if another lead exists with the same first 10 characters in the "Company" field #inSalesforce

Identify duplicate leads salesforce if another lead exists with the same first 6 characters in the "Company" field

Create record-triggered flow on leads that would update a text field with the first 6 characters of the Company field with this formula: LEFT({!$Record.Company},10)

Create a matching rule with this text field - Exact match and use it in a duplicate rule.

Note that the record-triggered flows only work for newly created/updated records. For existing ones, you would need to update the text field manually (maybe with the data loader) or create a scheduled flow running once that would update the text field with the same formula