The ultra power saving mode on my old Samsung Galaxy S7 did something similar. You put it in ultra power saving mode and it turns everything to black and white

The ultra power saving mode on my old Samsung Galaxy S7 did something similar. You put it in ultra power saving mode and it turns everything to black and white and only gives you access to a few number of apps that you select. I found it a very handy feature while travelling but ended up keeping my phone in that mode for the majority of its life after I discovered it. I wish my iPhone had a similar feature.