Actually there’s already an off-the-shelf solution for this, namely Liana wallet. It supports the MiniScript language, which lets you build wallets automatically based on different inheritance scenarios you want to plan for.

Just as a few examples:

Using Liana you could create a 2-of-3 multisig setup that decays into a 1-of-3 after a certain time period ^{say, time = X}. Then, you’d give one of the keys  to your heir/s ahead of time.

Another opt for you :
After a certain delay ^T1, a particular key (let’s say key #1 from the 2-of-3 multisig) gets spending rights. Again, your heir/s would need that key and its descriptor in advance to use it.

You can go even further and assign different time delays for each key ^{T2 for key #2, T3 for key #3,} etc and give control for your stash to different heirs.