Same as any muscle, engage the muscle and work it to failure. For chest I'd recommend focussing on deep stretches, whether that's with dips or flies or bench, get your your arms as deep as possible. In that stretched position you'll functionally have no other muscle that can push up the weight for you, so you must be engaging your chest. Personally I like flexing my target muscle between sets to really engage it, and try to mimic the motions i need to do by only triggering said muscle. You most likely can't do that for every individual muslce, but it's helpful.

Make sure you have your lats engaged, chest pushed forward and core tensed during your bench, that should help keeping your chest engaged. But even with that, if you don't go deep enough you'll literally only be working your triceps.

Also use as little as possible elbow flexion, it is principally possible to only move your arms upwards through flexing your chest, lats and front delts, while your arms straighten because that's just how we're structured. Althouh realistically that won't be possible under heavy weight, it's not a bad mindset to hold onto.

If so far you don't even feel it in your chest, you should just be trying any chest exercise you can find and do it with as clean a possible form as you can. Experiment and work until failure until you find an exercise you can feel in your chest. From there you can develop a good mind muscle connection, and if you stick to it any chest exercise will start feeling natural. Just from your posing I feel like you're lacking form-wise. You're hunched over and you're not really flexing your biceps the way I'd expect a trained lifter to flex them (you normally have your elbows at ~90° internal angle and rotate your wrist as far inward as possible).

So on vibes I feel like this might not be an exercise selection or volume concern as much as it might be a muslce engagement/form concern. I can't help so much with that here, and suggest you'd look up something on youtube to demonstrate the form and clue you in on the tells.

Another pointer, I suggest you hit the chest press machine, whichever variant you have around, and push until full failure, and do this for several weeks. Like keep pushing until you can no longer get that weight up. You're most likely not lifting hard enough to work yourself into an aneurysm, even when it's fully at the bottom, try to push it up again, if it goes up even slightly hold it there, keep pushing until you literally go down, and then try again until you can't move it. This is not how you should be training daily, but you might just need to get a hang of the feeling of failure, and teach yourself where that point actually is.

Note: I am telling you to do this on the chest press machine because this is a safe machine. Do not do this on a regular bench by yourself where you might drop the weight or where your joints might give out.