You either have to create new coins and breach the 21 million limit, or you have to siphon coins from somewhere other than the block fees.
Getting coins from other place than transaction fees means that you have to take them from the hodlers. And that can be done by using reversed coinage: you can check, in which block number some coin was created, and take a fee based on the number of confirmations. So, if you want to take one satoshi per 0.01 BTC from everyone, then if someone has 1 BTC, it means taking 100 satoshis per block. So, that means all coins will be taken after 1000000 blocks. That means, on average after 10 million minutes (around 19 years), each hodler will lose everything. Then, that hodler will have a choice: sign those coins, and send them as fees, or not sign those coins, and effectively get them excluded from the circulation.
So, that simple example means that getting a fixed tail supply fee as a single satoshi per 0.01 BTC in every block is too much. You can change amounts, make it percentage-based, again, it is all about proportions.