can use maxdop on online modifying column in mssql 2019?

I want to change data type of a column of my table in SQL Server 2019. My table has 50,000,000 row and it's very important. I want to do this operation online and also handle maxdop to avoid CPU over usage. I wrote this query but I got syntax error:

Alter table Customers
alter column FirstName char(16) not null
with (online = on, maxdop = 4)