Spokesperson for Ukraine's airforce says the F16's Ukraine is receiving have been modified by the US, they've added a upgraded radar system to the planes which increases the range of the radar
It's hard to know what radar the planes have been upgraded too. Older F16s were flying around with radar that could detect targets at 150km and engage targets at 50km. There was an upgrade program to change this to a new radar with 300km detection range.
But there is also currently a new program to equip an even further upgraded radar system which increases target engagement range to 150km and allows for engaging multiple targets at once.
Its hard to know what Ukraine is getting but if their F16s have the full upgrades that are technically available then they'd be able to detect targets over 300km and engage targets 150km away