S&P500 index fund- how to invest?

I’ve been dabbling in SG stocks and have an RSP for STI ETF. I am thinking of buying an index fund for S&P500.
Is there a way of buying an S&P500 index fund WITHOUT needing a CDP? If so, which funds and which platforms?
(Long story… My relative keeps tabs on my CDP transactions and she doesn’t believe in index funds…she thinks she can do better…)

for SG ETF, just buy singtel and the 3 banks is 40+% of the ETF. So yes I dun like SG ETF.

just buy ETF not listed on SGX which is foreign ETF

You can buy S&P500 index either directly from US market or UK market or HK market.
If you buy from US market, the downside is that there will be a 30% withholding tax on the dividend.
I think for UK market is 15% withholding tax on dividend but it is less liquid.
HK - I am not sure.
If you don’t want any purchase to be seen on the CDP transaction, you can buy through the stockbroking firms - prefunded or margin account. Then it wouldn’t appear on the CDP account.