You can find the code that generate order receipt number in point_of_sale\static\src\js\models.js

you can override the function and add your customization.

here is the origin function:
generate_unique_id: function() {
// Generates a public identification number for the order.
// The generated number must be unique and sequential. They are made 12 digit long
// to fit into EAN-13 barcodes, should it be needed

function zero_pad(num,size){
var s = ""+num;
while (s.length < size) {
s = "0" + s;
}
return s;
}
return zero_pad(this.pos.pos_session.id,5) +'-'+
zero_pad(this.pos.pos_session.login_number,3) +'-'+
zero_pad(this.sequence_number,4);
},

Hello sir,

Did you manage to find a solution for this?

Thank you in advance