For AI gen art -- What type of system specs (including video card) do you currently have? You can download local AI tools and models for free, but your system specs will matter. If you have a decent system (> 8GB video RAM), then you can download tools like comfyui or automatic1111 and then download models (refer to civitai for best central repo of models). There's thousands of online tutorials for setup and configuration, so just use google to find a tutorial and follow it.
For AI gen coding -- you can use free tools like chatgpt or gemini or whatever to get help with coding. Just note that they are very, very often wrong and can easily get stuck in error loops (they say do A, then you have bug, then they say do B to fix A's bug, then you get another bug, then to fix that bug, they tell you to do A again and you're stuck in a loop and they aren't smart enough to figure out the root cause). It can be helpful for minor code and sometimes do okay, but you need to understand what you're doing because it can't make a complete working game for you.
For AI gen story/writing -- you can also use free tools like chatgpt or gemini or whatever (same as with coding). Just note it won't get into naughty bits, but it can be very useful for story boarding, outlining, plot tracking, story threads, brainstorming, etc. There's other paid AI models that can get into naughty bits, but I don't think there's any free ones. The actual dialogue and text can feel very generic if you copy/paste it directly into your game, so it still requires a human touch to make it read well, but it's a very useful tool for the backend (outlining, tracking, brainstorming, etc.).