Have you looked at the schematic?
This thread is originally about the XIAO_ESP32C3, which has high current consumption and is not suitable for use with AA or AAA non-rechargeable batteries. You should have originally posted a separate topic about XIAO_RP2040.
As far as XIAO_RP2040 is concerned, there is no need to step down the voltage as long as it is below 7.5V.
How do I connect the LEDs?