There are a few different thru axle standards.
Front wheel Might be 15x100 or 15x110 (Boost).
Rear could be 12x148mm (Boost... most likely) or 12x142 (unlikely) or 12x157 (Super Boost... not sure how widespread this has become).
How easy it is to convert one axle type to another depends on the hub in question, though most manufacturers are making it easier these days due to the reality that a new axle standard comes out every three months.