UTXO can hold any amount of bitcoin, if you say 10 BTC then clearly you can fit 10 BTCs into one UTXO by consolidating it and it can be cheaper to transact compared to two 5 BTC UTXOs.

How large it should be depends on your preference, for example, if you are going to hold it for the long term and will sell all 10BTC at once when the desired price reached then holding it in one address is the wise choice but if you are someone who wants to spend BTC for purchases then don't hold more than 1 BTC in my opinion or the receiver can find how much your balance.