I like Stephen.R's suggestion - something like this:
StarTech.com Thunderbolt 3 to Dual HDMI 2.0 Adapter - 4K 60Hz Thunderbolt 3 Certified - Dual Monitor HDMI Video Converter Adapter - Mac & Windows compatible - Dual 4K Display HDMI (TB32HD24K60)
smile.amazon.com
and then two HDMI to DVI cables - these are inexpensive passive cables since HDMI and DVI are electrically compatible.
Or a much cheaper router, but consumes two USB-C ports, there are USB-C to DVI cables:
Cable Matters USB C to DVI Cable (USB-C to DVI Cable) 6 ft - Thunderbolt 4 / USB4 / Thunderbolt 3 Port Compatible with MacBook Pro, Dell XPS 13, 15, HP Spectre x360, Surface Pro
smile.amazon.com
Also USB-C to DVI female adapters so you can use existing DVI cables, but I prefer the integrated the cable above without needing an adapter:
Cable Matters USB C to DVI Adapter (USB-C to DVI Adapter) in Black - Thunderbolt 4 / USB4 / Thunderbolt 3 Port Compatible with MacBook Pro, Dell XPS 13, 15, HP Spectre x360, Surface Pro and More
smile.amazon.com
And then your HDMI capable monitor plugged directly to HDMI port on mac mini