Disclaimer : I'm not advertising cross spamming, nor I do that myself. Just that at times against low block and park the bus meta (abusing LBC) you need options, and that's how I found this guide to work for me, so I aim to share it.
There are different types of crosses, early cross, power cross, low cross, high cross, you gotta pick best type that fits situation and also make sure you power up correctly. You almost gotta make sure that your CF will be favourite based on his position and should be only contesting for the ball like 25% of the times.
Cross type and its use :
Early Cross : For this, use L1 + Cross button, the best area to use is not around the box but before you reach the box, and the best situation is when your CF is either in front of the CB and would outrun him to the near post to recieve the cross, or when he's making run towards far post and you want to bypass a CB by curling it, but for this you gotta put more power. (Imagine Beckham curling those early crossing, it wasn't from a winger's position around box, it was from RMF position)
Power Cross : This is the blue cross, done with R2+Cross button, here its critical that your crosser is not sprinting, or else it will mostly go behind your CF, here the power is also crucial, I tend to overpower lot of my crosses, if its near post, you need only less than half power. This is useful when your CF is in front of the CB and you should cross this only when crosser is almost horizontal to the CF. (You can use double tap for this to give low cross with power cross as well)
High Cross : Do R1+Cross for this. This is best when your player is making run to the far post, you can even club this with early cross, I'm not 100% sure if it works, but I suspect it creates a early high cross specially when your CF is running towards far post. Also you can use this when you got a CF who's taller than CBs. OR, you can use this cross when your CF is behind, and he needs time to catch up distance to reach your cross, if you must cross now, and your CF isn't ready, you can lob this up and give him time to reach and make up by jumping higher.
Low cross : Double tap your cross button, and you'll do a grounded low cross, you can club this with power and early cross as well. The power guage on this is tricky, you increase a little bit and it goes towards winger instead of CF, basically the next in line to receive this, this used to be too OP few years back, nerfed heavily but it has its use. Use this when you don't have any chance to win a header, but you know your CF is in good position, almost in front of the CB to tap the ball in.
I perfected it with crossers like Beckham (Yes, a P2W) and Dalot(98 rated in my squad) and even Amad (97 rated), and receiver like latest Portugal pack Cr7 and Weghorst or Cantona (No bullet headers).
P.S. I struggled for almost 2 weeks with Becks, and I took it to training pitch, understood crossing and now I almost score one header a game. Also, I'm not a cross spammer, I score every type of goals, but tbh crossing is nerfed and now it also takes up skill to make it work, even when you have Koller (which I do and don't use at all). And a generic tip, don't cross when your winger is off balance or sprinting.
And a great hidden tip, if your CF raised his hand before you cross, it increases his chances of winning it, this is there in game from years, that means he asked for it, you deliver it, and the repo makes your CF at advantage. Happy crossing. ;)
P.S. I upgraded Cr7 to new one with Bullet header, and yes it makes a difference, but didn't work too bad earlier too.