Welcome!
I’ve found the best way to stretch my playing is to listen to songs I love and find basslines that are slightly intimidating for me to learn. Nothing impossible, just enough to push my limit.
It takes perseverance, but I’ve found with age (and kids) I have a bit more of that than I did when I was first learning to play as a teenager.
I then record and post the outcomes on YT/FB/IG which keeps me honest (if I’m not playing it well enough to put out in the world, have I really learnt it?)
Might not work for everyone, but I’ve found this to be a great way to keep challenging myself.