As this XKCD cartoon suggests, we've got the whole password thingy quite wrong. We've made things too hard for ourselves. Using a passphrase rather than an incomprehensible password may be a better approach. Have a look at this passphrase generator. Note that some systems <cough>DET<cough> still require that additional numbers or symbols are used.

https://www.useapassphrase.com/

Separate passphrases/passwords MUST be used on different sites. Many browsers (Chrome, Safari, Edge, Firefox etc) now keep track of these logins for you and can sync between different devices. Personally, I use a commercial password manager (1Password) for which I pay an annual subscription.