Rather than thinking in percentages, I prefer to think in terms of multiples of anticipated annual spending.
So, at retirement, I would hope to have around 10 years of anticipated spending, over and above any State contributory pension, in “safe” assets (cash, bonds) with the balance in “growth” assets (equities, real estate).
So if your relative anticipates spending €25k per year, they would aim to have €250k in safe assets at retirement, with the balance in equities.
Your relative could gradually de-risk the portfolio over the next 10 years to achieve this allocation.