Look no further than LTspice. It's effectively the industry standard now and is pretty much instinctive to use once you realise that the gate component on the header bar means "components" - and there you'll find your voltage sources, NPNs and PNPs and route to opamps (including its generic versions which don't always need their own power supplies) and other specialist items. You can later use it with Kicad for 3D renderings of what your board will look like and I believe KiCAD also has some integration with FreeCAD so you can knock up 3D printed components or integrate your board into either its own casework or its part of another project. I've used LTspice for about 15 years now and have nothing but praise for it. There are a few quirks but they come fairly deep into using it and for this you should ideally be a member of the LTspice Groups.io group where you'll find a glittering array of experts who won't get snotty with you in a way that you might have come to expect on StackExchange or GroupDIY. Membership is free and you might find it worth keeping notes on the hurdles you come across in your early days on LTspice as this is an area that many of us have forgotten and so are not always as helpful as we could be with raw newcomers. If you can remember whatthe problem was and how you worked around it you could be of considerable help to future newbies. Good luck, and you'll love it!