In general 3-node clusters do not require separate disk or file share witness. Might help: https://www.starwindsoftware.com/blog/understand-failover-cluster-quorum
Dynamic Quorum is enabled by default since Windows Server 2012. It will automatically assign votes, in case node fails. In case you want to add additional vote to your cluster or one of the nodes is located in a DR location, I would recommend you to configure file share witness.
In addition, if you want to configure redundant witness, you can use StarWind VSAN to configure disk witness.
Note: Posts are provided “AS IS” without warranty of any kind, either expressed or implied, including but not limited to the implied warranties of merchantability and/or fitness for a particular purpose.