Hi,
You can create an automated action in the db, which we will read the next sequence from the ir.sequence record and assign it to the field in your model.

Steps to do:
   * Create a record in ir.sequence table
   * Ensure base_automation module is installed in db
   * Create automated action, select model as needed model and trigger on create
   * Add python code to assign the sequence value for field

See the example shown here:  Generate Sequence Using Automated Action In Odoo

Thanks