Restoring from Time Machine on a smaller capacity internal SSD

My Macbook Pro 2018 2.9GHz 6-core Intel Core i9, 32GB RAM, 2TB SSD, Radeon Pro Vega 20 with 4GB of HBM2 memory which was a high end CTO machine in Nov 2018 which costed me $4,824 has stopped working.

Within the Extended warranty period the logic board was replace twice, and now a month ago it has again conked off. Apple is saying that this machine is now Vintage and do not have the spares for it. This was a big shock to me that the machine is now just a paper weight as I an not getting any decent buy back for it either.

Now I do not want to buy a CTO machine considering spares are difficult to get but how can I get my Time machine restored on to a machine with 512GB internal SSD? My time machine backup is for almost full 2TB.