eGPU + RTX A4500 20gb on a RTX 3070 8gb laptop

hi right now i have a Lenovo P1 Gen4 with i7-11850H, RTX 3070 8gb and 32gb Ram.

I can handle medium projects very well but when moving to a project with a lot of geometry it reaches the limit of 8gb of vram and it closes.

For me it is very important to have only one computer to always be able to work in the same ecosystem, for that reason I am thinking of buying one (Sonnet eGPU Breakaway Box 750ex) with a 20gb RTX A4500.

since my problem is not the speed but rather the capacity of vram.

the question would be if an eGPU that graphics cards have to cope with around 21 GBit /s being 80% of its speed, what would be more than what I have right now, will the 20gb of vram be used at 100%?

D5 Render Version:
Graphics Card: