I want to transfer my all things from my old Mac mini to my new iMac

Please refer to Move your content to a new Mac.

Yes, I can. Migration Assistant is an installed program provided by Apple for transferring your files from your old computer to your new computer. It is very easy to use. Be sure to read and follow its instructions. Basically, the process is as follows.

You first begin by starting the process of setting up your new computer. You will be asked if you wish to transfer files. Respond YES and follow the instructions you will be given.

You will be told to turn both computers on and activate Migration Assistant in the old computer.

The computers should be connected with a USB cable to facilitate the transfer.  Wi-Fi is simply not suited for a transfer of so much data and corruption often results.  Do not use it. It can corrupt or lose data.

You will be given several options as to what to transfer. You will likely want to transfer your settings and preferences.

You can transfer all or none of your files. You do not have an option to select certain files to transfer. If you wish to do that, then do so manually.

The old computer's operating system will not be transferred. No data from the old computer is erased.

Allow for up to an hour for the transfer process to complete once you start it.

It should set up the new computer the same as the old one.

Enjoy your new Mac.

I hope this is helpful. Good luck.