https://docs.ordinals.com/ tells you what sat ranges your utxos contain. Example:
https://ordinals.com/output/3ea3bc8d7991869294ce43450eefee0de47a592417a59bd440e7d15fe74f4824:15 This utxo has 600 sats: 45039459700-45039460300 (600 sats). There are 5000000000 mined in a block from the first epoch. You can observe that this particular utxo has satoshis from the first Bitcoin mined by satoshi in block 9.
If you want to preserve some rare sats (let's assume you find them in a bigger utxo), you can split that utxo into 3: sats before the offset of the ones you're interested in, sats that you're interested in, sats after the ones you're interested in. Then you keep the utxo with the sats ur interested in safe. there are already tools built for this.
that txid : 3ea3bc8d7991869294ce43450eefee0de47a592417a59bd440e7d15fe74f4824
has a fee of 10200 sats. so the first 10200 sats of that tx are given back to the miners.
yep if output 15: in your eyes is "600 sats: 45039459700-45039460300" in your eyes.. its actually not
because the fee has been taken and so output 15 is actually 45,039,469,900-45,039,470,500
technically it further along then that because if you start doing real economic counting of sat positions from the original coin creation of block reward from the historic data, each input spend of fee puts each output off by the fee, meaning after several transaction taints/descendants later, each output is off by the fee amount. meaning the transaction in question is off by a larger magnitude
have a nice day calculating its real position of output 15