Win10 desktop like older versions of non server OS's does support "file sharing" connections.
Currently Win10 Pro can allow up to 20 "concurrent" file sharing connections with the caveat that once you hit 5 or 6 concurrent connections the shared location may not show up in file explorer until you drop below that threshold.
SEE HERENote, file sharing is not 100% the same as a "file server".
Windows desktop (Like Win10) does not have a lot of advanced features found in a file server OS like Domain controller, Active Directory, DHCP (doles out IP addresses dynamically for your server domain) along with advanced domain security and Administrator tools.
Windows server OSs do have a desktop UI (User Interface) which means you could potentially use Windows server OS as a desktop to a certain point. But, to use Windows Server as a desktop OS you will find that it is less optimized and far more expensive to purchase for that purpose.
If you are not concerned about high security, you can enable file and printer sharing on any desktop PC with Win10 Pro and create local network of shared file resources for a small quantity of PCs to connect to with Win10 pro..
Win10 Home may have considerable limitations above what Win10 pro offers so your mileage may vary..
If you want the full file server experience with user logins and higher security for your local network then Windows File server on a dedicated PC may be the way you need to go. Windows server can be installed on pretty much any PC hardware provided you have all of the proper drivers for your hardware, does not need to be installed on "server" hardware for causal light duty use.. Heck, I have installed Windows server into a VMs on a Win10 Pro PC and it works fine on VMs..
On edit..
If you were to decide to setup dedicated Win server local network, check your local Craigs list for used off lease Dell or HP servers.. I see a lot of 12 - 16 processor core servers being offered on my local CL for $100-$200 each without HDs.. Many of those servers can run SATA drives which are cheap and plentiful, for faster and more robust HDs SAS drives are better but much more expensive..
A non server substitute if you just want simple file sharing is a NAS unit (Network Attached Storage) which is a Linux based network file sharing unit..