chip more than 3/8” and the surface will be pretty uneven. Tiles come unbonded easily if you don’t have a uniform substrate or if it’s dirty. Spreading a self leveling just ensures you don’t have to reset tiles again later. Plus thinset wasn’t made to be applied thick. You’ll have issues with curing times and bonding problems.

Now if you’re grinding, then just grind level and no self leveling needed.