Yes, you can define global or per core visual preferences.
First you need to define the parameters. You can download some here (+instructions)
https://misterreplay.com/mister-fpga-gu ... apter19xiv
To set one of these as your global setting, simply edit your MiSTer.ini file and change this line:
preset_default= MrRePlay/01_Default_CRT
Where the path/filename is to your specific folder and preset. Make sure the line isn't commented out (no semicolon ; in front of the line)
You can also do it per core by adding a core exception. This has to be placed at the very end of your INI file like this:
; Core name exception note here
[Core name]
preset_default=MrReplay/01_Default_CRT
Save and restart to take effect.