Use mempool.space.
It shows the median and the minimum and maximum fee rate used in a block.
Blockchain explorer mempool.space can be considered the best tool to check all fees data within any block. It's my default browser in my Electrum wallet.
Besides, i always use blockchair.com which is a good alternative as well. It shows the best fee rate to get your transaction confirmed and updates instantly. I prefer blockchair because it offers a navigator addon which can be easily installed and friendly-used.
In general, most open-source wallets provide a feature of knowing the average fees before sending, which can be trusted without resorting to an external site.