active directory – what is the best practice to let employees connect to company server remotly

We have server with domain controller in our company and all employees are connected to the server through user accounts and have access to specific folders based on their privileges.

Due to COVID pandemic, we need to let our employees work from home for several days.
what is the best practice to achieve this task?
what are the requirements (Real IP, VPN Server or role .. etc) knowing that our server OSis win server 2012 r2.