will a magsafe 2 (60 watt) charger for a 2015 13" macBook Pro charge a new 2021 13" macBook Pro laptop

MagSafe-2 is not compatible with MagSafe-3 in the following:

connector size and shape -- it won't fit! (by design)

required protocol used to negotiate charging rates -- MagSafe-3 uses a variant of USB-C Power Delivery Protocol, ONLY.

charge capacity

BiciBoy wrote:

will a magsafe 2 (60 watt) charger for a 2015 13" macBook Pro charge a new 2021 13" macBook Pro laptop

There is no "2021" 13" MBP...(?)

MacBook Pro (13-inch, 2020, Two Thunderbolt 3 ports) - Technical Specifications

MacBook Pro (13-inch, 2020, Four Thunderbolt 3 ports) - Technical Specifications

MacBook Pro (13-inch, M1, 2020) - Technical Specifications

MacBook Pro 14- and 16-inch - Technical Specifications ...

Find the right power adapter and cable for your Mac notebook ...

About Mac power adapters - Apple Support