You can create manual incremented sequence by using a microflow. To do so you need the following activities:
1- retrieve objects of the entity you want to increment
2- count these objects
3- create your object with sequence set to formatDecimal($count +1, ‘00000’)
Hope this helps.
Have a look at using an attribute of type AutoNumber. This will give you an increasing number for each entity created that has an AutoNumber attribute.
You can then use the StringPadLeft action in the Community Commons module in the Marketplace to help provide leading zeros if necessary.
I hope this helps.