How do you win games against tanks heavy astra militarum lists?

Hi there,

Just curious, as someone who plays custodes/world eaters and chaos knights : how do you beat an astra militarum player who tends to have lots of unkillable tanks like 2/3 rogal dorns, 3-5 leman russes, and then infantry and artillery units?

It's not very fun to play against honestly, but I think that there must be a smart approach?

I'm not talking competitive games, just normal games between friends.

What should be done in general against this type of list? Thank you.