Custom Paintjob/livery

I'm planning my first proper all-out bike build as a bit of a homage to my first ever road bike, an Ammaco xr5800 which my dad handed down to me. I wanna do a remodelling of it's current paint job, basically keep it recognisable as the stock paint job but reimagined as what if the bike was made sometimes in the past 2 years; modernise it's look. Does anyone know how all those builds on Instagram with custom paint and decals get it done? I just wanna know how to go about it