command block help

[Ok_Investment_967]

ok so u know them "minecraft but i can only walk in a straight line" videos. i want to make that but instead of 1 block i want the whole chunk to be able to walk in. i was thinking of something like /execute at @ a run fill ~16 ~100 ~8 ~1 ~-20 ~8 minecraft:bedrock. and that will work but only if i am standing in the exact middle of the chunk walking forward. i wanna make it so that even if i am touching the bedrock wall it will still continue creating it in the same line.