
Can you clarify your question or provide more details?
If you're storing clear text passwords in a data source like SQL/SharePoint/Excel, there is no way to prevent users from accessing the column that contains the passwords if the user has underlying rights to access the data source.
There are some posts in the ideas forum about adding the ability to encrypt specific fields in the data source. That might be of interest to you.
https://powerusers.microsoft.com/t5/Power-Apps-Ideas/Ability-to-encrypt-select-fields/idi-p/102905