New user, Garmin questions

[Bigtrout]

I just got a little Garmin Striker 4 for kayak fishing, mainly to find bottom features, depth and perhaps brushpiles. Not really intending to search for fish necessarily. But, brand new at this and having watched multiple YouTubes, right out of the box I’m a bit confused.
Does the size of the fish arch change with the depth? In other words, will a 6” fish at 7’ appear as a much larger (and stronger) arch than the same fish at 15’? Also, again at a shallower depth, will smaller limbs and things look like large structures?
Nearly every YouTube tutorial shows water depths of 20’-30’ and what I’m seeing at 12’-15’ and shallower looks much different. Im using 77kHz to “widen the cone” in this shallower water but I think I’m only getting a couple feet of coverage so I’m wondering if that magnifies, in essence, what I’m seeing.
So...not sure of how to interpret what I see or even what I’m looking at for sure.

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