Depending on your hardware you might be able to generate images without using any service! For all its quirks, downsides and moral stuff, it can be a lot of fun to play with. If you’re on Apple hardware, try my favorite tool, Draw Things https://apps.apple.com/it/app/draw-things-ai-generation/id6444050820?l=en-GB that is free, without ads and worst case scenario it runs like crap on your device if it’s not very modern. If you’re not using Apple gear, Enfugue (that still supports Macs) https://github.com/painebenjamin/app.enfugue.ai is quite simple and easy to install.
And obviously what’s probably the most popular option, the behemoth that is known as automatic1111 stable diffusion webui https://github.com/AUTOMATIC1111/stable-diffusion-webui that’s not the most user friendly solution but…
Perfectly sensible is the only thing I can say about it :)