or simply add a cost for a template and you are better/different aspect of your legacy.
I.E:
Warforged:
1. +60ft darkvision
2. +1 AC with proficient armor or unarmed defense 13+dex
3. Awake during long rest, still needs 6hrs
4. integrated tool. Pick one tool that is part of your chassis. you have proficiency+expertise in that tool.
5. construct resilience:
- You have advantage on saving throws against being poisoned, and you have resistance to poison damage.
- You don’t need to eat, drink, or breathe.
- You are immune to disease.
- You don't need to sleep, and magic can't put you to sleep.
you keep all your features of base race and add this on top of it.