I think that entirely avoiding the upper body is a big mistake- I understand that you may not want to gain any upper body mass, but there is a big difference between that and not training upper body at all. There’s a good reason there are not many programs like you suggest. Gaining upper body mass without high testosterone (i.e being a man or taking drugs) is not easy- you will not look like the Crossfit games girls without (at least) years of hard work.
Having said that, since you are a free individual and can choose your own goals, my tips for designing a “lower body only” program would be:
Weight train 3 x per week, condition 2-3 times per week. For conditioning, swim (freestyle and butterfly)- you need the shoulder/tricep/oblique work on this program! Rowing is a second choice, but not the day before lifting. Weight training: I assume you are female and just starting out, so if your 3-5rm squat is in the 30-100kg range, the following volume should be OK: Squat 2x week, say 5x5. Deadlift 1x per week 2-3 x5- ie monday squat, Wed deadlift, Fri Squat. On a linear progression, or a 5,3,1 progression without deloads (the detail doesn’t matter too much- just intermediate reps and make progress). Follow the big lift with 2 or 3 movements for 3 sets of 8-12- choose your own adventure with various lunge variations, good mornings, RDL, Glute ham raises, kettle bell swings (more reps- e.g. sets of 20), hamstring curls etc. Do some core work every weight training day- leg raises, round the world, ab wheel, sit ups etc.
If you are more advanced, just do Smolov- there’s not a lot of room for anything other than squatting in there!