The transition from trading small to trading real size, and how much of it is psychological rather than strategic is important knowledge.

When I was trading with a few hundred dollars, taking a 10% loss meant losing $50. Uncomfortable but manageable. When you start trading with 10k, 20k, 50k per position, that same 10% loss is 5k. The pattern on the chart is identical, your strategy is the same, but your brain responds completely differently because the number on the screen now carries real weight.
I noticed that when I first sized up, I started breaking my own rules. Taking profits too early because the gains felt "big enough," moving my stop loss because the potential loss felt too painful, hesitating on entries because the position size made me second-guess my setup. And none of these problems had anything to do with my strategy, they were entirely about my relationship with the amount of money at risk.
What helped me through this was sizing up very gradually and giving myself time to normalise each level. Going from 1k positions to 5k positions, sitting there for weeks until that size felt boring and routine, then moving to 10k. Each jump takes time to absorb mentally, and if you skip levels or size up too fast after a good streak, you'll almost certainly give it back because your emotions aren't calibrated for that size yet.
Your strategy doesn't need to change as your account grows. Your mental relationship with risk does, and most people underestimate how long that adjustment takes.