It isn’t possible to get new leather which is produced without animal cruelty - the fact is that a sentient animal was slaughtered just for that bags or those shoes (or food). Obviously some animals are kept in better conditions whilst alive but they all suffer, at the end.
You could look at second hand or recycled leather if you want to keep to leather.
Or consider a vegan leather alternative.
LaBante and Wilby are good for bags.
Will’s vegan shoes are great quality and ensure fair conditions for those that make the shoes. They also do some bags. They carbon offset products.
Beyond Skin has boots and shoes but I’ve found they haven’t lasted as long as Will’s (tend to be dressier styles though than Will’s).
Elvis and Kreusse make bags and accessories from recycled fire hoses and donate a portion of profit to charity. Not cheap but as you mentioned you don’t want disposable fashion well worth considering as an investment.
Toms is another good ethical company for shoes and they have a vegan range.
Matt and Nat have shoes and bags and a lot of stuff made from recycled products.
For clothes People Tree is good. They have some really nice materials and unusual pieces. Free People is another one to consider.
Fashion Conscience is a website with various different brands which may be worth checking out.
For coats and jackets Save the Duck is an option for alternatives to down. I believe Patagonia has good ethical credentials (but don’t quote me on that as I haven’t bought from them) and have some jackets filled with modern materials including recycled plastics.
Hope that helps.