In keyboard options there’s a checkbox to permanently make the function keys stay on the touchbar.
all it does is swap over the fn functionality so that instead of showing you the fun keys it shows you the touchbar instead.
theres no way to physically swap out the touchbar though, just the software option to get them back permanently or app specific. I customised mine so I’m happy with it, i hardily used the function keys anyway for most apps so it’s a welcome change that needs some more software tweaks I think.