Should I sell my apartment?

I bought an apartment(PPOR) in St Kilda for 500K just before Covid hit and now looking to upsize and buy another apartment in the same area up to 750K, spoke with a REA and he reckons I can only get 480K out of it, if I deduct the advertising and real state fee(nearly 25K) and pay off the mortgage I will have around 50K which is quite a loss considering that I paid 15K LMI when I bought it, now I’m wondering is it best if I rent out the current apartment (still have to contribute $500/month to cover the mortgage and Body Corp,…) and use negative gearing to reduce my taxes (I’m making 200k/year) or get rid off the apartment and increase my deposit?

Cheers