When it comes to this i've come to learn that steel plate seed phrase is enough, just disclose the location to your family and you're set. no complicated thing or anything like that.
This may not be enough. Either your "heirs" will not be able to restore access to the wallet without knowing how to use the seed phrase, or they will allow this information to "leak" into the network \ hackers \ strangers. That is, it is necessary to leave precise instructions on how to properly use the seed phrase.
Just consider it part of our belonging when we're still alive much like our phones. Other option like multi sig, custody, etc just feels like a burden.
I think it would be right to leave in addition to the seed phrase the hardware wallet, which is easy to use, but at the same time doesn'tt allow the seed phrases to "leak" into the wrong hands. Hardware wallet is a kind of
foolproof protection. That is, HW device + seed phrase as a backup.