It won't be just the strongest network, I'm pretty sure there will be a hierarchy, like the way most phones by default select 4G if available, then 3G, and fall back to 2G only if there's nothing else, even though 2G will often be the strongest signal.
But does it not have the "preferred network type" setting in your mobile network settings? It may be under "advanced" (as it is on my Pixel), or it may be somewhere non-standard (because Samsung always rearrange the menus their own way), but it would be surprising if it isn't there at all.
(There's always the hidden "testing" menu, unless Samsung or your carrier have removed that. Type *#*#4636#*#* into your dialer - no need to press anything, when you enter the last character it will open the menu. Under "phone information" there is an option to change preferred network type. But use that menu with care, note what the original setting is before changing anything, and don't fiddle with anything you don't understand: that menu is hidden because there are things in there that can cause problems if you set them wrongly).