I have 2010 IMac desktop can I connect that to Mac Mini?

Using Target Display Mode (TDM), a 2010 iMac must be the 27-inch version to act as display for a supported Mac computer. No Macs made after 2019 are supported for TDM, as are any running a newer macOS version that 10.15 Catalina.

See: Use your iMac as a display with target display mode

TDM is dead tech. Apple started its deprecation in Late 2014 and threw the last shovel of dirt in its face in early 2020.

The old iMac computer cannot be used as a monitor for the new Mac mini.