Given that a pair of monitors are not engineered to 'daisy chain' (see below), you must use an adapter. There are many options for purchase, some can provide a wide array of I/O options for different cable types, and some that simply output to 2 HDMI connections (and allow for 4k signal). Assuming your monitors have HDMI inputs, that would be your more basic solution. You would want to do a product search for "thunderbolt 3 to dual HDMI adapter".
If in the future you get monitors with thunderbolt ports, you would be able to use them for daisy chaining a spectrum of configurations, as shown in this infographic.